Revert "drm/nouveau/gsp: add support for GA100"

Revert "drm/nouveau/gsp: add support for GA100"

This reverts commit 20e0c197802c545db220157fafd567a10f2b7672.

Despite claiming to add GA100 support, that commit actually has quite
a few problems.  It falsely claims that there is no VBIOS.  GA100 does
have a VBIOS, but it has no display engine, so it cannot use the
PRAMIN method the read VBIOS and must fall back to using PROM.

For whatever reason, the VBIOS on GA100 has an "Init-from-ROM"
(IFR) header where the PCI Expansion ROM would normally be found.
So to find that ROM, Nouveau needs to parse the IFR header.

The commit also falsely claimed that there is no graphics (GR) engine.

So rather than try to fix that commit, just revert it and start over
from scratch.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Link: https://patch.msgid.link/20260430223838.2530778-2-ttabi@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>