pixel_inc and row_inc work differently on OMAP2/3 and OMAP4+ DSS. On
OMAP2/3 DSS, the pixel_inc is _not_ added by the HW at the end of the
line, after the last pixel, whereas on OMAP4+ it is.

The driver currently works for OMAP4+, but does not handle OMAP2/3
correctly, which leads to tilted image when row_inc is used.

This patch adds a flag to DISPC driver so that the pixel_inc is added
when required.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>