drm/radeon: Use DIV_ROUND_UP()

Use DIV_ROUND_UP() instead of hand rolling it. Just a drive-by change.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479498793-31021-4-git-send-email-ville.syrjala@linux.intel.com

drivers/gpu/drm/radeon/radeon_legacy_crtc.c

@@ -477,9 +477,8 @@ retry:
 	crtc_offset_cntl = 0;
 
 	pitch_pixels = target_fb->pitches[0] / (target_fb->bits_per_pixel / 8);
-	crtc_pitch  = (((pitch_pixels * target_fb->bits_per_pixel) +
-			((target_fb->bits_per_pixel * 8) - 1)) /
-		       (target_fb->bits_per_pixel * 8));
+	crtc_pitch = DIV_ROUND_UP(pitch_pixels * target_fb->bits_per_pixel,
+				  target_fb->bits_per_pixel * 8);
 	crtc_pitch |= crtc_pitch << 16;
 
 	crtc_offset_cntl |= RADEON_CRTC_GUI_TRIG_OFFSET_LEFT_EN;