iommu/vt-d: Remove global g_iommus array

The g_iommus and g_num_of_iommus is not used anywhere. Remove them to
avoid dead code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lore.kernel.org/r/20220702015610.2849494-6-baolu.lu@linux.intel.com


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