acpi: pc: vga: use AcpiDevAmlIf interface to build VGA device descriptors

acpi: pc: vga: use AcpiDevAmlIf interface to build VGA device descriptors

NB:
We do not expect any functional change in any ACPI tables with this
change. It's only a refactoring.

NB2:
Some targets (or1k) do not support acpi and CONFIG_ACPI is off for them.
However, modules are reused between all architectures so CONFIG_ACPI is
on.  For those architectures, dummy stub function definitions help to
resolve symbols.  This change uses more of these and so it adds a couple
of dummy stub definitions so that symbols for those can be resolved.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20221017102146.2254096-2-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Ani Sinha <ani@anisinha.ca>
CC: Bernhard Beschow <shentey@gmail.com>
Signed-off-by: Ani Sinha <ani@anisinha.ca>
Message-Id: <20221107152744.868434-1-ani@anisinha.ca>