drm/panel-simple: Add a timing for the Raspberry Pi 7" panel

The Raspberry Pi 7" 800x480 panel uses a Toshiba TC358762 DSI
to DPI bridge chip, so there is a requirement for the timings
to be specified for the end panel. Add such a definition.

upstream link: https://lore.kernel.org/lkml/20220131191517.30249-1-detlev.casanova@collabora.com/T/



Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Rahul T R <r-ravikumar@ti.com>