[MIPS] make plat_perf_setup() static
[MIPS] make plat_perf_setup() static

There is no need for the plat_perf_setup() function to be global,
so make it static.

Successfully build-tested using default configs for Malta, Atlas
and SEAD boards.

Runtime test successfully performed by booting the Malta 4Kc board
up to the shell prompt.

Signed-off-by: Dmitri Vorobiev <c182faaccd98c386beebc1be0ad63ed5bc4ff904@gmail.com>
Signed-off-by: Ralf Baechle <92f48d309cda194c8eda36aa8f9ae28c488fa208@linux-mips.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs