ARM: SAMSUNG: Remove Exynos specific code from devs, s5p-pm-irq and pm-gpio.c

This file is only compiled when SAMSUNG_ATAGS is enabled, hence not
for Exynos platform.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
[kgene.kim@samsung.com: squashed into one]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>