dt-bindings: panel-simple: Add compatible for Sharp LS020B1DD01D

Add a compatible string for the Sharp LS020B1DD01D 2" HQVGA TFT LCD
panel, and remove the old sharp,ls020b1dd01d.txt documentation which is
now obsolete.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200109003000.119516-2-paul@crapouillou.net