ARM: EXYNOS: Bring exynos4-dt up to date

This commit brings exynos4-dt in line with recent changes to
mach-exynos tree, specifically:

 - Fixes build break related to replacing plat/exynos4.h with
   common.h in commit cc511b8d ("ARM: 7257/1: EXYNOS:
   introduce arch/arm/mach-exynos/common.[ch]")

 - Converts machine to use CONFIG_MULTI_IRQ_HANDLER as done for
   other machines in commit 4e44d2cb ("ARM: exynos4: convert
   to CONFIG_MULTI_IRQ_HANDLER")

 - Adds restart specifier as done for other machines in commit
   9eb48595 ("ARM: 7262/1: restart: EXYNOS: use new restart hook")

Signed-off-by: Karol Lewandowski <k.lewandowsk@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>