EXYNOS: Add clock for SPI

EXYNOS: Add clock for SPI

Add api to calculate and set the clock for SPI channels

Signed-off-by: James Miller <jamesmiller@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Signed-off-by: Hatim Ali <hatim.rv@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
Conflicts:
	arch/arm/cpu/armv7/exynos/clock.c
	arch/arm/include/asm/arch-exynos/clk.h

Change-Id: Ie772ece94f18e66a5e0836b833a6cdf3c3562811