drm/msm/dsi: Use DIV_ROUND_UP instead of conditional increment on modulo

This exact same math is used to compute bytes_in_slice above in
dsi_update_dsc_timing(), also used to fill slice_chunk_size.

Fixes: b9080324 ("drm/msm/dsi: add support for dsc data")
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Patchwork: https://patchwork.freedesktop.org/patch/508935/
Link: https://lore.kernel.org/r/20221026182824.876933-4-marijn.suijten@somainline.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/dsi/dsi_host.c

@@ -1807,9 +1807,7 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc)
 	 * params are calculated
 	 */
 	groups_per_line = DIV_ROUND_UP(dsc->slice_width, 3);
-	dsc->slice_chunk_size = dsc->slice_width * dsc->bits_per_pixel / 8;
-	if ((dsc->slice_width * dsc->bits_per_pixel) % 8)
-		dsc->slice_chunk_size++;
+	dsc->slice_chunk_size = DIV_ROUND_UP(dsc->slice_width * dsc->bits_per_pixel, 8);
 
 	/* rbs-min */
 	min_rate_buffer_size =  dsc->rc_model_size - dsc->initial_offset +