drm/panel: Add Rocktech jh057n00900 panel driver

Support Rocktech jh057n00900 5.5" 720x1440 TFT LCD panel. It is a MIPI
DSI video mode panel.

The panel seems to use a Sitronix ST7703 look alike (most of the
commands look similar to the ST7703's data sheet but use a different
number of parameters). The initial version of the DSI init sequence
(including sleeps) were provided by the vendor. Sleeps were reduced
considerably though to speed up initialization.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1a9ce687be283c66dfb26d1dfb52a7bf695090fa.1554114302.git.agx@sigxcpu.org