MIPS: Remove unused declarations in asm/cmp.h

These functions have been removed since
commit 7fb6f7b0af67 ("MIPS: Remove deprecated CONFIG_MIPS_CMP"),
so remove them.

Signed-off-by: Gaosheng Cui <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/include/asm/cmp.h

···
  */
 struct task_struct;
 
-extern void cmp_smp_setup(void);
-extern void cmp_smp_finish(void);
-extern void cmp_boot_secondary(int cpu, struct task_struct *t);
-extern void cmp_init_secondary(void);
-extern void cmp_prepare_cpus(unsigned int max_cpus);
-
-/* This is platform specific */
-extern void cmp_send_ipi(int cpu, unsigned int action);
 #endif /*  _ASM_CMP_H */