msm: kgsl: Remove unneeded debug message

All the callers of adreno_dispatcher_queue_cmd send the return code
from the function back to the user.  Stop printing the error code
in the kernel log - sometimes the error is legitimate (like
-ERESTARTSYS) but it worries folks watching the logs.

Change-Id: Ic0dedbadd2e054dd0af1c1099647233466baba37
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>