misc: bcm-vk: unlock on error in bcm_to_h_msg_dequeue()

Unlock before returning on this error path.

Fixes: 111d746b ("misc: bcm-vk: add VK messaging support")
Acked-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YBfyb+jU5lDUe+5g@mwandaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/bcm-vk/bcm_vk_msg.c

@@ -855,7 +855,8 @@ s32 bcm_to_h_msg_dequeue(struct bcm_vk *vk)
 				 * that is fatal.
 				 */
 				dev_crit(dev, "Kernel mem allocation failure.\n");
-				return -ENOMEM;
+				total = -ENOMEM;
+				goto idx_err;
 			}
 
 			/* flush rd pointer after a message is dequeued */