xtensa: signal: include headers for function prototypes

Add <asm/syscall.h> to satisfy the xtensa_rt_sigreturn() prototype
warning.
Add <asm/processor.h> to satisfy the do_notify_resume() prototype
warning.

arch/xtensa/kernel/signal.c:246:17: warning: no previous prototype for 'xtensa_rt_sigreturn' [-Wmissing-prototypes]
arch/xtensa/kernel/signal.c:525:6: warning: no previous prototype for 'do_notify_resume' [-Wmissing-prototypes]
  525 | void do_notify_resume(struct pt_regs *regs)
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20230920052139.10570-7-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/processor.h

@@ -220,6 +220,7 @@ struct mm_struct;
 extern unsigned long __get_wchan(struct task_struct *p);
 
 void init_arch(bp_tag_t *bp_start);
+void do_notify_resume(struct pt_regs *regs);
 
 #define KSTK_EIP(tsk)		(task_pt_regs(tsk)->pc)
 #define KSTK_ESP(tsk)		(task_pt_regs(tsk)->areg[1])

arch/xtensa/kernel/signal.c

@@ -26,6 +26,8 @@
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
 #include <asm/coprocessor.h>
+#include <asm/processor.h>
+#include <asm/syscall.h>
 #include <asm/unistd.h>
 
 extern struct task_struct *coproc_owners[];