[MIPS] Make KGDB compile on UP

Building UP kernel with KGDB enabled produces the following errors and warning
(fatal due to -Werror in arch/mips/kernel/Makefile):

In file included from arch/mips/kernel/gdb-stub.c:142:
include/asm/smp.h:25:1: "raw_smp_processor_id" redefined
In file included from include/linux/sched.h:69,
                 from arch/mips/kernel/gdb-stub.c:126:
include/linux/smp.h:88:1: this is the location of the previous definition
In file included from arch/mips/kernel/gdb-stub.c:142:
include/asm/smp.h:62: error: redefinition of 'smp_send_reschedule'
include/linux/smp.h:102: error: previous definition of 'smp_send_reschedule' was here
include/asm/smp.h: In function `smp_send_reschedule':
include/asm/smp.h:65: error: dereferencing pointer to incomplete type
arch/mips/kernel/gdb-stub.c: At top level:
arch/mips/kernel/gdb-stub.c:660: warning: 'kgdb_wait' defined but not used

Fix the errors by not directly including <asm/smp.h> (which is already included
by <linux/smp.h>) and the warning by enclosing kgdb_wait() in #ifdef CONFIG_SMP.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/gdb-stub.c

@@ -139,7 +139,6 @@
 #include <asm/system.h>
 #include <asm/gdb-stub.h>
 #include <asm/inst.h>
-#include <asm/smp.h>
 
 /*
  * external low-level support routines
@@ -656,6 +655,7 @@ void set_async_breakpoint(unsigned long *epc)
 	*epc = (unsigned long)async_breakpoint;
 }
 
+#ifdef CONFIG_SMP
 static void kgdb_wait(void *arg)
 {
 	unsigned flags;
@@ -668,6 +668,7 @@ static void kgdb_wait(void *arg)
 
 	local_irq_restore(flags);
 }
+#endif
 
 /*
  * GDB stub needs to call kgdb_wait on all processor with interrupts