ArmVirtPkg/ArmVirtQemu: Revert "limit ACPI support to v5.0 and higher"
    
    This reverts commit e0692789058ee2c0099f88852503c16dbb0bae4e.
    
    The default value for PcdAcpiExposedTableVersions is now set to 0x20
    for Aarch64 systems. Setting this PCD in ArmVirtPkg/ArmVirtQemu.dsc
    is no longer necessary.
    
    Signed-off-by: Samer El-Haj-Mahmoud <samer@elhajmahmoud.com>
    Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
    Reviewed-by: Laszlo Ersek <lersek@redhat.com>