ARM: EXYNOS: use s5p-timer for UniversalC210 board

Commit 069d4e74

 ("ARM: EXYNOS4: Remove clock event timers using
ARM private timers") removed support for local timers and forced
to use MCT as event source. However MCT is not operating properly
on early revision of EXYNOS4 SoCs. All UniversalC210 boards are
based on it, so that commit broke support for it. This patch
provides a workaround that enables UniversalC210 boards to boot
again. s5p-timer is used as an event source, it works only for
non-SMP builds.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>