ARM: EXYNOS: Fix for stall in case of cpu hotplug or sleep

This patch adds remove_irq in place of disable_irq which
is correct equivalent function for setup_irq used in
exynos4_mct_tick_init.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
Tested-by: Inderpal Singh <inderpal.singh@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>