[media] VPU: mediatek: fix null pointer dereference on pdev

pdev is being null checked, however, prior to that it is being
dereferenced by platform_get_drvdata.  Move the assignments of
vpu and run to after the pdev null check to avoid a potential
null pointer dereference.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Tiffany Lin <tiffany.lin@mediatek.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/mtk-vpu/mtk_vpu.c

@@ -534,9 +534,9 @@ static int load_requested_vpu(struct mtk_vpu *vpu,
 
 int vpu_load_firmware(struct platform_device *pdev)
 {
-	struct mtk_vpu *vpu = platform_get_drvdata(pdev);
+	struct mtk_vpu *vpu;
 	struct device *dev = &pdev->dev;
-	struct vpu_run *run = &vpu->run;
+	struct vpu_run *run;
 	const struct firmware *vpu_fw = NULL;
 	int ret;
 
@@ -545,6 +545,9 @@ int vpu_load_firmware(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	vpu = platform_get_drvdata(pdev);
+	run = &vpu->run;
+
 	mutex_lock(&vpu->vpu_mutex);
 	if (vpu->fw_loaded) {
 		mutex_unlock(&vpu->vpu_mutex);