[MIPS] SMTC: Fix modpost warning.

WARNING: vmlinux.o(.text+0xcf54): Section mismatch: reference to .init.text:smp_bootstrap (between 'smtc_boot_secondary' and 'ipi_interrupt')
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/smtc.c

@@ -524,7 +524,7 @@ void mipsmt_prepare_cpus(void)
  * (unsigned long)idle->thread_info the gp
  *
  */
-void smtc_boot_secondary(int cpu, struct task_struct *idle)
+void __cpuinit smtc_boot_secondary(int cpu, struct task_struct *idle)
 {
 	extern u32 kernelsp[NR_CPUS];
 	long flags;