drm/rockchip: use DIV_ROUND_UP macro for calculations.

Replace the open coded calculation with the more concise and readable
DIV_ROUND_UP macro.
Signed-off-by: Wambui Karuga <wambui.karugax@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20200109142057.10744-1-wambui.karugax@gmail.com

drivers/gpu/drm/rockchip/rockchip_drm_vop.h

@@ -328,7 +328,7 @@ static inline uint16_t scl_get_bili_dn_vskip(int src_h, int dst_h,
 {
 	int act_height;
 
-	act_height = (src_h + vskiplines - 1) / vskiplines;
+	act_height = DIV_ROUND_UP(src_h, vskiplines);
 
 	if (act_height == dst_h)
 		return GET_SCL_FT_BILI_DN(src_h, dst_h) / vskiplines;