rk30_hotdog_ti_defconfig: enable CONFIG_DDR_FREQ
rk30: board-rk30-box: change ddr frequency table

Change normal mode ddr frequency to 300MHz, and change
video mode ddr frequency to 400MHz.

When play 1080p video, will set the video mode in user space.
arm: plat-rk: do not clear video_state when release

OMXCodec do not have a member to keep a open file descriptor,
and we do not want to add one. So set the video_state when begin
and end video play.