Commit 3d42f1dd ("vgaarb: Keep adding VGA device in queue") assumes
the first device is an integrated GPU. However, on AMD platforms an
integrated GPU can have higher PCI device number than a discrete GPU.

Integrated GPU on ACPI platform generally has _DOD and _DOS method, so
use that as predicate to find integrated GPU. If the new strategy
doesn't work, fallback to use the first device as boot VGA.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210519135723.525997-1-kai.heng.feng@canonical.com