Windows added by the BIOS are not marked as 64bit because they are
usually not changeable anyway.

This fixes large BAR support on my new Ryzen build system.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>