drm/panel: simple: Add missing display timing flags for KOE TX26D202VM0BWA

KOE TX26D202VM0BWA panel spec indicates the DE signal is active high in
timing chart, so add DISPLAY_FLAGS_DE_HIGH flag in display timing flags.
This aligns display_timing with panel_desc.

Fixes: 8a07052440c2 ("drm/panel: simple: Add support for KOE TX26D202VM0BWA panel")
Signed-off-by: Liu Ying <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Neil Armstrong <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panel/panel-simple.c

···
 	.vfront_porch = { 3, 5, 10 },
 	.vback_porch = { 2, 5, 10 },
 	.vsync_len = { 5, 5, 5 },
+	.flags = DISPLAY_FLAGS_DE_HIGH,
 };
 
 static const struct panel_desc koe_tx26d202vm0bwa = {