drm/imx/dw-hdmi: drop unused module alias

drm/imx/dw-hdmi: drop unused module alias

The driver has never supported anything but OF probe so drop the unused
platform module alias which was incorrectly added by commit 3d1b35a3d9f3
("drm: imx: imx-hdmi: convert imx-hdmi to drm_bridge mode").

Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250924092643.26113-2-johan@kernel.org
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>