drm/panel: Add a driver for the TPO TPG110

The TPO (Toppoly) TPG110 is a pretty generic display driver
similar in vein to the Ilitek 93xx devices. It is not a panel
per se but a driver used with several low-cost noname panels.

This is used on the Nomadik NHK15 combined with a OSD
OSD057VA01CT display for WVGA 800x480.

The driver is pretty minimalistic right now but can be
extended to handle non-default polarities, gamma correction
etc.

The driver is based on the baked-in code in
drivers/video/fbdev/amba-clcd-nomadik.c which will be
decomissioned once this us upstream.

Cc: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111175406.27646-1-linus.walleij@linaro.org