ARM: EXYNOS: use v7_exit_coherency_flush macro for cache disabling

ARM: EXYNOS: use v7_exit_coherency_flush macro for cache disabling

A common macro v7_exit_coherency_flush available which does the below
tasks in the seqeunce.
-clearing C bit
-clearing L1 cache
-exit SMP
-instruction and data synchronization

So removing the local functions which does the same thing and use the
macro instead.

Signed-off-by: Leela Krishna Amudala <leela.krishna@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
[cw00.choi@samsung.com: tested on exynos3250 based board]
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>