EFI: retrieve and expose Apple device properties

EFI: retrieve and expose Apple device properties

Apple's EFI drivers supply device properties which are needed to
support Macs optimally. They contain vital information which cannot be
obtained any other way (e.g. Thunderbolt Device ROM). They're also used
to convey the current device state so that OS drivers can pick up where
EFI drivers left (e.g. GPU mode setting).

Reference: Linux commit 58c5475aba67706b31d9237808d5d3d54074e5ea (see
there for the full original commit message, only the initial part of
which is being reproduced above)

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>