video: da8xx-fb: support lcdc v2 timing register expansion

TI LCD controller version 2 adds some extra bits in a register to
increase the available size to represent horizontal timings. This
patch allows the fbdev driver to utilize those extra bits.
This will become important for driving an HDMI encoder from the lcd
controller where some of the VESA/CEA modes require quite large porches.

Signed-off-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>