msm: kgsl: Make ACD QMP message sending failure non fatal

If ACD fails to send its state through the QMP mailbox, we do not get
the power saving as expected. An error message will do and need not
fail probe.

Change-Id: I821d0d3c774cc45726a8c7b281d226ff5da83fa5
Signed-off-by: Mohammed Mirza Mandayappurath Manzoor <mmandaya@codeaurora.org>