iommu/vt-d: Create RMRR mappings in newly allocated domains

Currently the RMRR entries are created only at boot time.
This means they will vanish when the domain allocated at
boot time is destroyed.
This patch makes sure that also newly allocated domains will
get RMRR mappings.

Signed-off-by: Joerg Roedel <jroedel@suse.de>