ARM: SAMSUNG: Fix build warnings because of unused codes

This patch removes following unused codes for removing build warnings.

arch/arm/plat-samsung/adc.c:438: warning: unused variable 'flags'
arch/arm/mach-s5pv210/clock.c:176: warning: 's5pv210_clk_ip4_ctrl' defined but not used

Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>