acpi: parse Alias object

acpi: parse Alias object

Since QEMU commit
  47a373faa6 (acpi: pc/q35: drop ad-hoc PCI-ISA bridge AML routines and let bus ennumeration generate AML)
SeaBIOS fails to parse ISA bridge AML with:

   parse_termlist: parse error, skip from 92/517
   ...
   ACPI: no PS/2 keyboard present

due to Alias term in DSDT which isn't handled by SeaBIOS properly.
Add dumb Alias parsing which just skips over term,
so the rest of AML could be parsed successfully.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reported-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20221118142755.3879231-1-imammedo@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>