adding file for use by tda998x driver
adding extra debug, still a WIP
video: da8xx-fb fixing incorrect porch mappings

The driver was mapping the wrong fbdev margins to the
front porch / back porch for both vertical and horizontal
timings.

This patch corrects it so that:

hfp = right margin
hbp = left margin
vbp = upper margin
vfp = lower margin
adding some extra modes into dts for fbdev on am335x
fixing return value error checking in da8xx-fb.c
fixing pixel clock of 640x480 mode in dts file