config: arm: exynos5250: Define CONFIG_SYS_CACHELINE_SIZE

XHCI stack driver needs this to align buffers to
CacheLine boundary. So define the same to be '64'

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Dan Murphy <dmurphy@ti.com>
Cc: Marek Vasut <marex@denx.de>