drm/nouveau/TBDdevinit: don't fail when PMU/PRE_OS is missing from VBIOS

[ Upstream commit 0a6986c6595e9afd20ff7280dab36431c1e467f8 ]

This Falcon application doesn't appear to be present on some newer
systems, so let's not fail init if we can't find it.

TBD: is there a way to determine whether it *should* be there?

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>