This was lost when code was refactored. Patch restores previous behavior.

It is still not clear whether this is the right one. Due to the way we
detect DM abstraction, partitions on DM are skipped, we fall through to
generic detection which ends up in assuming parent device is BIOS disk.

It is useful to install GRUB on VM disk from the host. But it also means
that GRUB will mistakenly allow install on real system as well.

For now let's fix regression; future behavior needs to be discussed.

Closes: 45163

Fixes device detection with large number of devices.

Reported by Tim Wallberg <twalberg@comcast.net>

Found by: Coverity scan.

	follow the same algorithm to avoid method mismatch. Don't assume
	DMRAID- UUID to mean full disk but instead check that mapping is linear.

	long as performance doesn't suffer.