media: s5p-mfc: Clear workbit to handle error condition

During error on CLOSE_INSTANCE command, ctx_work_bits was not getting
cleared. During consequent mfc execution NULL pointer dereferencing of
this context led to kernel panic. This patch fixes this issue by making
sure to clear ctx_work_bits always.

Fixes: 818cd91a ("[media] s5p-mfc: Extract open/close MFC instance commands")
Cc: stable@vger.kernel.org
Cc: linux-fsd@tesla.com
Signed-off-by: Smitha T Murthy <smitha.t@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/platform/samsung/s5p-mfc/s5p_mfc_ctrl.c

@@ -468,8 +468,10 @@ void s5p_mfc_close_mfc_inst(struct s5p_mfc_dev *dev, struct s5p_mfc_ctx *ctx)
 	s5p_mfc_hw_call(dev->mfc_ops, try_run, dev);
 	/* Wait until instance is returned or timeout occurred */
 	if (s5p_mfc_wait_for_done_ctx(ctx,
-				S5P_MFC_R2H_CMD_CLOSE_INSTANCE_RET, 0))
+				S5P_MFC_R2H_CMD_CLOSE_INSTANCE_RET, 0)){
+		clear_work_bit_irqsave(ctx);
 		mfc_err("Err returning instance\n");
+	}
 
 	/* Free resources */
 	s5p_mfc_hw_call(dev->mfc_ops, release_codec_buffers, ctx);