msm: ADSPRPC: Avoid race condition during map creation and free

Avoid race condition for concurrent threads to not to create and
free the map.

Change-Id: I219353500024092165b527688cfbf1dda3665f01
Acked-by: Himateja Reddy <hmreddy@qti.qualcomm.com>
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>