csky: Fixup -Wmissing-prototypes warning

Cleanup the warnings:

arch/csky/kernel/ptrace.c:320:16: error: no previous prototype for 'syscall_trace_enter' [-Werror=missing-prototypes]
arch/csky/kernel/ptrace.c:336:17: error: no previous prototype for 'syscall_trace_exit' [-Werror=missing-prototypes]
arch/csky/kernel/setup.c:116:34: error: no previous prototype for 'csky_start' [-Werror=missing-prototypes]
arch/csky/kernel/signal.c:255:17: error: no previous prototype for 'do_notify_resume' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:150:15: error: no previous prototype for 'do_trap_unknown' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:152:15: error: no previous prototype for 'do_trap_zdiv' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:154:15: error: no previous prototype for 'do_trap_buserr' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:157:17: error: no previous prototype for 'do_trap_misaligned' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:168:17: error: no previous prototype for 'do_trap_bkpt' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:187:17: error: no previous prototype for 'do_trap_illinsn' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:210:17: error: no previous prototype for 'do_trap_fpe' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:220:17: error: no previous prototype for 'do_trap_priv' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:230:17: error: no previous prototype for 'trap_c' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:57:13: error: no previous prototype for 'trap_init' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:12:5: error: no previous prototype for '__vdso_clock_gettime64' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:18:5: error: no previous prototype for '__vdso_gettimeofday' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:24:5: error: no previous prototype for '__vdso_clock_getres' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:6:5: error: no previous prototype for '__vdso_clock_gettime' [-Werror=missing-prototypes]
arch/csky/mm/fault.c:187:17: error: no previous prototype for 'do_page_fault' [-Werror=missing-prototypes]

Link: https://lore.kernel.org/lkml/20230810141947.1236730-17-arnd@kernel.org/Reported-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

arch/csky/include/asm/ptrace.h

@@ -96,5 +96,7 @@ static inline unsigned long regs_get_register(struct pt_regs *regs,
 	return *(unsigned long *)((unsigned long)regs + offset);
 }
 
+asmlinkage int syscall_trace_enter(struct pt_regs *regs);
+asmlinkage void syscall_trace_exit(struct pt_regs *regs);
 #endif /* __ASSEMBLY__ */
 #endif /* __ASM_CSKY_PTRACE_H */

arch/csky/include/asm/sections.h

@@ -7,4 +7,6 @@
 
 extern char _start[];
 
+asmlinkage void csky_start(unsigned int unused, void *dtb_start);
+
 #endif /* __ASM_SECTIONS_H */

arch/csky/include/asm/traps.h

@@ -40,4 +40,19 @@ do { \
 
 void csky_alignment(struct pt_regs *regs);
 
+asmlinkage void do_trap_unknown(struct pt_regs *regs);
+asmlinkage void do_trap_zdiv(struct pt_regs *regs);
+asmlinkage void do_trap_buserr(struct pt_regs *regs);
+asmlinkage void do_trap_misaligned(struct pt_regs *regs);
+asmlinkage void do_trap_bkpt(struct pt_regs *regs);
+asmlinkage void do_trap_illinsn(struct pt_regs *regs);
+asmlinkage void do_trap_fpe(struct pt_regs *regs);
+asmlinkage void do_trap_priv(struct pt_regs *regs);
+asmlinkage void trap_c(struct pt_regs *regs);
+
+asmlinkage void do_notify_resume(struct pt_regs *regs,
+			unsigned long thread_info_flags);
+
+void trap_init(void);
+
 #endif /* __ASM_CSKY_TRAPS_H */

arch/csky/kernel/vdso/vgettimeofday.c

@@ -3,24 +3,35 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
+extern
+int __vdso_clock_gettime(clockid_t clock,
+			 struct old_timespec32 *ts);
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
 	return __cvdso_clock_gettime32(clock, ts);
 }
 
+int __vdso_clock_gettime64(clockid_t clock,
+			   struct __kernel_timespec *ts);
 int __vdso_clock_gettime64(clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
 	return __cvdso_clock_gettime(clock, ts);
 }
 
+extern
+int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
+			struct timezone *tz);
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 			struct timezone *tz)
 {
 	return __cvdso_gettimeofday(tv, tz);
 }
 
+extern
+int __vdso_clock_getres(clockid_t clock_id,
+			struct old_timespec32 *res);
 int __vdso_clock_getres(clockid_t clock_id,
 			struct old_timespec32 *res)
 {