ARM: EXYNOS: Fix soft reboot hang after suspend/resume

Upon wake-up, clear the sleep mode set in INFORM1 register.

Signed-off-by: Inderpal Singh <inderpal.singh@samsung.com>
Tested-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>