ARM: exynos: Enable support for ARM architected timers

ARM architected timer can be used together with Exynos MultiCore Timer
driver, so enable support for it. Support for ARM architected timers is
essential for enabling proper KVM support.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>