MIPS: Make a needlessly global symbol static in arch/mips/kernel/smp.c

The variable cpu_callin_map is needlessly defined global, so let's
make it static now.

Build-tested using malta_defconfig.
Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/smp.c

@@ -44,7 +44,7 @@
 #include <asm/mipsmtregs.h>
 #endif /* CONFIG_MIPS_MT_SMTC */
 
-volatile cpumask_t cpu_callin_map;	/* Bitmask of started secondaries */
+static volatile cpumask_t cpu_callin_map;	/* Bitmask of started secondaries */
 int __cpu_number_map[NR_CPUS];		/* Map physical to logical */
 int __cpu_logical_map[NR_CPUS];		/* Map logical to physical */