drm/rockchip: vop: fix NV12 video display error

fixup the scale calculation formula on the case
src_height == (dst_height/2).

Signed-off-by: Mark Yao <[e-mail]>
Reviewed-by: Sandy huang <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/rockchip/rockchip_drm_vop.h

···
 
 	act_height = (src_h + vskiplines - 1) / vskiplines;
 
+	if (act_height == dst_h)
+		return GET_SCL_FT_BILI_DN(src_h, dst_h) / vskiplines;
+
 	return GET_SCL_FT_BILI_DN(act_height, dst_h);
 }