ARM: EXYNOS: Add missing static storage class specifier in pmu.c file

arch/arm/mach-exynos/pmu.c:318:14: warning:
symbol 'exynos5_list_both_cnt_feed' was not declared. Should it be static?
arch/arm/mach-exynos/pmu.c:332:14: warning:
symbol 'exynos5_list_diable_wfi_wfe' was not declared. Should it be static?

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>