drm/stm: ltdc: fix data enable polarity

Wrong DISPLAY_FLAGS used to set the data enable polarity.
Signed-off-by: Yannick Fertré <yannick.fertre@st.com>
Acked-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1553874620-31468-1-git-send-email-yannick.fertre@st.com

drivers/gpu/drm/stm/ltdc.c

@@ -555,7 +555,7 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
 	if (vm.flags & DISPLAY_FLAGS_VSYNC_HIGH)
 		val |= GCR_VSPOL;
 
-	if (vm.flags & DISPLAY_FLAGS_DE_HIGH)
+	if (vm.flags & DISPLAY_FLAGS_DE_LOW)
 		val |= GCR_DEPOL;
 
 	if (vm.flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)