drm/ast: vga: Clear EDID if no display is connected

Do not keep the obsolete EDID around after unplugging the display
from the connector.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 2a2391f8 ("drm/ast: vga: Transparently handle BMC support")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241015065113.11790-3-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_vga.c

@@ -29,6 +29,8 @@ static int ast_vga_connector_helper_get_modes(struct drm_connector *connector)
 	if (ast_connector->physical_status == connector_status_connected) {
 		count = drm_connector_helper_get_modes(connector);
 	} else {
+		drm_edid_connector_update(connector, NULL);
+
 		/*
 		 * There's no EDID data without a connected monitor. Set BMC-
 		 * compatible modes in this case. The XGA default resolution