msm: vidc: Free up remaining memory in close session

Call msm_comm_smem_free() before freeing the list node
to free the buffer associated with the node. The function
is void if the buffer is already free'd.

CRs-Fixed: 2111809
Change-Id: Idce3d1457646744b71c07f8d698c0fbf1ff9d0d2
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>