x86/PVH: expose OEMx ACPI tables to Dom0

x86/PVH: expose OEMx ACPI tables to Dom0

What they contain we don't know, but we can't sensibly hide them. On my
Skylake system OEM1 (with a description of "INTEL  CPU EIST") is what
contains all the _PCT, _PPC, and _PSS methods, i.e. about everything
needed for cpufreq. (_PSD interestingly are in an SSDT there.)

Further OEM2 there has a description of "INTEL  CPU  HWP", while OEM4
has "INTEL  CPU  CST". Pretty clearly all three need exposing for
cpufreq and cpuidle to work.

Fixes: 8b1a5268daf0 ("pvh/dom0: whitelist PVH Dom0 ACPI tables")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>