ehea: Detect 16GB hugepages for firmware restriction

All kernel memory which is used for kernel/hardware data transfer must
be registered with firmware using "memory regions". 16GB hugepages
may not be part of a memory region due to firmware restrictions.
This patch modifies the walk_memory_resource callback fn to filter
hugepages and add only standard memory to the busmap which is later
on used for MR registration.

Signed-off-by: Thomas Klein <tklein@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>