msm: mhi_dev: Update verbosity level for MHI logs

Update the logging level type for MHI output log
to lower priority to avoid flooding the kernel
message logs.

Change-Id: I99c6897ce20e90f8f5a6e9940658c9ccd89179fb
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>