drm/panel: Add Ronbo RB070D30 panel

The Ronbo RB070D30 panel is a MIPI-DSI panel based on a Fitipower EK79007
controller and a 1024x600 panel.

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Konstantin Sudakov <k.sudakov@integrasources.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/3cc43c6051e89a52434053a38a36621acab7236e.1550650810.git-series.maxime.ripard@bootlin.com