drm/rockchip: cdn-dp: fix cdn-dp complie warning

fix warning:

drivers/gpu/drm/rockchip/cdn-dp-reg.c:632:24: warning:
  'val[1]' may be used uninitialized in this function [-Wmaybe-uninitialized]
  msa_misc = 2 * val[0] + 32 * val[1] +
Signed-off-by: Mark Yao <mark.yao@rock-chips.com>

drivers/gpu/drm/rockchip/cdn-dp-reg.c

@@ -592,7 +592,7 @@ static int cdn_dp_get_msa_misc(struct video_info *video,
 			       struct drm_display_mode *mode)
 {
 	u32 msa_misc;
-	u8 val[2];
+	u8 val[2] = {0};
 
 	switch (video->color_fmt) {
 	case PXL_RGB: