video: mxc_hdmi: Default to HDMI mode.

If we don't receive a valid EDID default to HDMI mode.  This is
an HDMI port and selecting DVI while getting a wider range of
resolutions you lose support for audio and cec.  Lets choose
modern and more functional interface as the fallback default.
dts: cbi/hb: Add a simple basic kernel commandline

In general this won't be selected, but provide it in case
a user wants to use directboot or hasn't properly setup their
uEnv.txt or uboot.scr.  This is another method for providing
the best chances a new kernel will boot.