[media] media: venus: venc: fix compile error in venc_close

This fixes the following compile error ocured when building
with gcc7:

drivers/media/platform/qcom/venus/venc.c:1150
venc_close() error: dereferencing freed memory 'inst'

by moving kfree as a last call.
Signed-off-by: NStanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/qcom/venus/venc.c

@@ -1145,10 +1145,10 @@ static int venc_close(struct file *file)
 	mutex_destroy(&inst->lock);
 	v4l2_fh_del(&inst->fh);
 	v4l2_fh_exit(&inst->fh);
-	kfree(inst);
 
 	pm_runtime_put_sync(inst->core->dev_enc);
 
+	kfree(inst);
 	return 0;
 }