drm/msm/dsi-staging: handle DSI command transfer during suspend

When a DSI command transfer is initiated from debugfs interface,
current error log does not give out adequate information. Handle
this scenario and modify logging appropriately.

Change-Id: I5c61d9ce5559631948ce91482644941aaf481349
Signed-off-by: Shashank Babu Chinta Venkata <sbchin@codeaurora.org>
Signed-off-by: Abhijith Desai <desaia@codeaurora.org>