drm/bridge: imx8mp-hdmi-pai: enable PM runtime

drm/bridge: imx8mp-hdmi-pai: enable PM runtime

There is an audio channel shift issue with multi channel case - the
channel order is correct for the first run, but the channel order is
shifted for the second run. The fix method is to reset the PAI interface
at the end of playback.

The reset can be handled by PM runtime, so enable PM runtime.

Fixes: 0205fae6327a ("drm/bridge: imx: add driver for HDMI TX Parallel Audio Interface")
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Liu Ying <victor.liu@nxp.com>
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Link: https://lore.kernel.org/r/20260130080910.3532724-1-shengjiu.wang@nxp.com