mips: add missing declarations

These are three more functions that are only called from assembler and
only need a declaration to avoid the -Wmissing-prototypes warnings:

arch/mips/kernel/signal.c:904:17: error: no previous prototype for 'do_notify_resume' [-Werror=missing-prototypes]
arch/mips/kernel/traps.c:370:6: error: no previous prototype for 'show_registers' [-Werror=missing-prototypes]
arch/mips/kernel/smp.c:352:17: error: no previous prototype for 'start_secondary' [-Werror=missing-prototypes]

Link: https://lkml.kernel.org/r/20231204115710.2247097-14-arnd@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@rothwell.id.au>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/mips/include/asm/processor.h

@@ -402,4 +402,6 @@ extern int mips_set_process_fp_mode(struct task_struct *task,
 #define GET_FP_MODE(task)		mips_get_process_fp_mode(task)
 #define SET_FP_MODE(task,value)		mips_set_process_fp_mode(task, value)
 
+void show_registers(struct pt_regs *regs);
+
 #endif /* _ASM_PROCESSOR_H */

arch/mips/include/asm/signal.h

@@ -31,5 +31,6 @@ extern struct mips_abi mips_abi_32;
 
 extern int protected_save_fp_context(void __user *sc);
 extern int protected_restore_fp_context(void __user *sc);
+void do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags);
 
 #endif /* _ASM_SIGNAL_H */

arch/mips/include/asm/smp.h

@@ -63,6 +63,8 @@ extern asmlinkage void smp_bootstrap(void);
 
 extern void calculate_cpu_foreign_map(void);
 
+asmlinkage void start_secondary(void);
+
 /*
  * this function sends a 'reschedule' IPI to another CPU.
  * it goes straight through and wastes no time serializing