imx: mx6: add clock api for lcdif

Implement mxs_set_lcdclk, enable_lcdif_clock and enable_pll_video.
The three API can be used to configure lcdif related clock when
CONFIG_VIDEO_MXS enabled.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
2 files changed