If the resolution of the TFT display is smaller than the maximum
resolution supported by the display controller, the display may be
connected to the driver output arrays with a horizontal and/or vertical
offset, leading to a shifted image.

Add support for specifying these offsets.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200115124548.3951-4-geert+renesas@glider.be