drm/nouveau/flcn: new code to load+boot simple HS FWs (VPR scrubber)

Adds the start of common interfaces to load and boot the HS binaries
provided by NVIDIA that enable the usage of GR.

ACR already handles most of this, but it's very much tied into ACR's
init process, and there's other code that could benefit from reusing
a lot of this stuff too (ie. VBIOS DEVINIT/PreOS, VPR scrubber).

The VPR scrubber code is fairly independent, and a good first target.

- adds better debug output to fw loading process, to ease bring-up/debug

v2:
- whitespace, 0->false

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