drm/i2c/tda998x prepare for tilcdc sync workaround

Add necessary support for flipping the hsync signal and shifting
the display to the right by a certain number of pixels.  Changes
only take effect if adjusted_mode is changed in fixup function.

Signed-off-by: Darren Etheridge <detheridge@ti.com>
drm/tilcdc fixup mode to workaound sync for tda998x

Add a fixup function that will flip the hsync priority and
add a hskew value that is used to shift the tda998x to the
right by a variable number of pixels depending on the mode.
This works around an issue with the sync timings that tilcdc
is outputing.

Signed-off-by: Darren Etheridge <detheridge@ti.com>