Now that we're supporting things like Ada and the GSP, there's situations
where we really need to actually know the display state that we're starting
with when loading the driver in order to prevent breaking GSP expectations.
The first step in doing this is making it so that we can read the current
state of IORs from nvkm in DRM, so that we can fill in said into into the
atomic state.

We do this by introducing an INHERIT ioctl to nvkm/nvif. This is basically
another form of ACQUIRE, except that it will only acquire the given output
path for userspace if it's already set up in hardware. This way, we can go
through and probe each outp object we have in DRM in order to figure out
the current hardware state of each one. If the outp isn't in use, it simply
returns -ENODEV.

This is also part of the work that will be required for implementing GSP
support for display. While the GSP should mostly work without this commit,
this commit should fix some edge case bugs that can occur on initial driver
load. This also paves the way for some of the initial groundwork for
fastboot support.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919220442.202488-11-lyude@redhat.com