drm/omap: DMM: In case of error/timeout in wait_status() print the reason

If the wait_status() fails either because of an error reported in the
STATUS register or because of a timeout waiting for the wait_mask, print
information which might help diagnose the reason.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>