drm/bridge: imx8mp-hdmi-tx: switch to DRM_BRIDGE_ATTACH_NO_CONNECTOR

drm/bridge: imx8mp-hdmi-tx: switch to DRM_BRIDGE_ATTACH_NO_CONNECTOR

The imx8mp-hdmi-tx one of many drivers based on dw-hdmi. dw-hdmi in turn
can operate in two different modes, depending on the platform data as set
by the driver:

 A. hdmi->plat_data->output_port = 0:
    the HDMI output (port@1) in device tree is not used [0]

 B. hdmi->plat_data->output_port = 1:
    the HDMI output (port@1) is parsed to find the next bridge

The imx8mp-hdmi-tx driver falls in case A. Switching to case B, which is
the current best practice, requires that the HDMI connector is always
described in the live device tree, and a previous commit ensured this is
always the case by adding an overlay in case the device tree does not
comply.

So now we can simply switch to the new mode and support
DRM_BRIDGE_ATTACH_NO_CONNECTOR.

Reviewed-by: Liu Ying <victor.liu@nxp.com>
Link: https://patch.msgid.link/20260407-drm-lcdif-dbanc-v4-10-247a16e61ef9@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>