drm/nouveau/kms/nv50-: create connectors based on nvkm info

- preparation for GSP-RM

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919220442.202488-43-lyude@redhat.com

drm/nouveau/disp: add output detect method

This will check the relevant hotplug pin and skip the DDC probe we
currently do if a display is present.

- preparation for GSP-RM.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919220442.202488-8-lyude@redhat.com

drm/nouveau/disp: expose conn event class

This removes some now-unnecessary nesting of workqueues.

v2:
- use ?: (lyude)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/disp: add conn method to query HPD pin status

And use it to bail early in DP detection and avoid futile AUX transactions.

This could be used on other connector types too in theory, but it's not
something we've ever done before and I'd rather not risk breaking working
systems without looking into it more closely.

It's safe for DP though. We already do this by checking an AUX register
that contains HPD status and aborting the transaction. However, this is
much deeper in the stack - after taking various mutexes, poking HW for no
good reason, and making a mess in debug logs.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drm/nouveau/disp: add connector class

Will be used to provide more solid driver interfaces in general, but
the immediate motivation is work towards fixing issues with handling
hotplug/DP IRQ events.

Its use is currently limited to where we support non-polled hotplug
already (ie. any GPU since NV40ish era, where our DCB handling works
well enough), until that gets cleaned up someday.

v2:
- use ?: (lyude)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>