dt-bindings: display: convert sharp,lq101r1sx01 to DT Schema

dt-bindings: display: convert sharp,lq101r1sx01 to DT Schema

This binding describes a panel with a secondary channel.

v3:
  - Add reg property and unit-address to dsi nodes (Rob)

v2:
  - add check for required properties if link2 is present (Rob)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200704102806.735713-4-sam@ravnborg.org