drm/nouveau/bios: add parsing of BIT M(v2) +0x03 table

We only support one kind of matching here (ramcfg strap), but it appears
alternate methods are possible.  I wrote a tool to scan our vbios repo
for other types, but did not see any used.  Hopefully this means there
aren't any in the wild that will now break.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>