msm: camera: mem_mgr: Add refcount to track in use buffers

The function cam_mem_mgr_release can unmap the buffers when in use.

This change prevents unmapping the buffers when in use.

CRs-Fixed: 3489559
Change-Id: I2e72e795d39ac15abfa56c19043c419a03686966
Signed-off-by: Shivakumar Malke <quic_smalke@quicinc.com>

drivers/cam_req_mgr/cam_mem_mgr.h

@@ -80,6 +80,9 @@ struct cam_mem_buf_hw_hdl_info {
  * @is_imported:    Flag indicating if buffer is imported from an FD in user space
  * @is_internal:    Flag indicating kernel allocated buffer
  * @timestamp:      Timestamp at which this entry in tbl was made
+ * @krefcount:      Reference counter to track whether the buffer is
+ *                  mapped and in use
+ * @smmu_mapping_client: Client buffer (User or kernel)
  * @presil_params:  Parameters specific to presil environment
  */
 struct cam_mem_buf_queue {
@@ -98,6 +101,8 @@ struct cam_mem_buf_queue {
 	bool is_imported;
 	bool is_internal;
 	struct timespec64 timestamp;
+	struct kref krefcount;
+	enum cam_smmu_mapping_client smmu_mapping_client;
 
 #ifdef CONFIG_CAM_PRESIL
 	struct cam_presil_dmabuf_params presil_params;