msm: ADSPRPC: Free private data on error conditions

Ensure the buffers associated with the file private data
is freed on error conditions.

Change-Id: I21e92ec066c362e4e8897a176ec2a58b762b077a
Acked-by: Himateja Reddy <hmreddy@qti.qualcomm.com>
Signed-off-by: Sathish Ambley <sathishambley@codeaurora.org>