For MNC207QS1-1 panel, Splash screen occur when switch from VT1 to VT2.
The BL_EN signal does not conform to the VESA protocol.
BL_EN signal needs to be pulled high after video signal.
So add prepare_to_enable to 200ms.

[ dianders: Adjusted subject prefix and added Fixes tag ]

Fixes: 0547692a ("drm/panel-edp: Add several generic edp panels")
Signed-off-by: Zhengqiao Xia <xiazhengqiao@huaqin.corp-partner.google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240301084006.14422-1-xiazhengqiao@huaqin.corp-partner.google.com