drm: panel: Add Starry KR070PE2T

The KR070PE2T is a 7" panel with a resolution of 800x480.

KR070PE2T is the marking present on the ribbon cable. As this panel is
probably available under different brands, this marking will catch
most devices.

As I can't find a datasheet for this panel, the bus_flags are instead
from trial-and-error. The flags seem to be common for these kind of
panels as well.

Signed-off-by: Pascal Roeleven <dev@pascalroeleven.nl>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200320112205.7100-3-dev@pascalroeleven.nl