drm: omapdrm: dss: replace ternary operator with max()

Fix the following coccicheck warning:

drivers/gpu/drm/omapdrm/dss/dispc.c:2454:21-22: WARNING opportunity for max()
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220517050208.121488-1-guozhengkui@vivo.com

drivers/gpu/drm/omapdrm/dss/dispc.c

@@ -2451,7 +2451,7 @@ static int dispc_ovl_calc_scaling_44xx(struct dispc_device *dispc,
 
 	*decim_x = DIV_ROUND_UP(width, in_width_max);
 
-	*decim_x = *decim_x > decim_x_min ? *decim_x : decim_x_min;
+	*decim_x = max(*decim_x, decim_x_min);
 	if (*decim_x > *x_predecim)
 		return -EINVAL;