x86: fixup config space size of CPU functions for AMD family 11h

Impact: extend allowed configuration space access on 11h CPUs from 256 to 4K

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>