ARM: EXYNOS: Remove unused non-dt support for dwmci controller

With device tree support enabled for dwmci controller, the unused
non-dt support for dwmci controller can be removed.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
[kgene.kim@samsung.com: updated as per Seungwon Jeon's pointing out]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>