drm: rp1: Use tv_mode from the command line and fix for Linux 6.6

Use the standard enum drm_connector_tv_mode instead of a private
enum and switch from the legacy to the standard tv_mode property.

Remove the module parameter "tv_norm". Instead, get tv_mode from
the command line and make this the connector's default TV mode.

Don't restrict the choice of modes based on tv_mode, but interpret
nonstandard combinations as NTSC or PAL, depending on resolution.
Thus the default tv_mode=NTSC effectively means "Auto".

Tweak the advertised horizontal timings for 625/50 to match Rec.601

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>