drm/panel: sharp: lq101r1sx01: Add delay after display on

After switching the display on (using the DCS display_on command), wait
for 6 frames (100ms at 60 Hz) to give the display more time to prepare.
Failing to do this results in the panel not initializing properly in a
large number of cases.

Signed-off-by: Thierry Reding <treding@nvidia.com>