drm/omap: panel-dsi-cm: fix remove()

Do not try to reset the panel after DSI has been
detached, since the DSI clocks may have been disabled
at this point. The panel will be disabled and unprepared
before being removed and a reset will be done when being
probed again.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201215104657.802264-38-tomi.valkeinen@ti.com