VT-d: drop undue address-of from check_cleanup_domid_map()

VT-d: drop undue address-of from check_cleanup_domid_map()

For an unknown reason I added back the operator while backporting,
despite 4.16 having c06e3d810314 ("VT-d: per-domain IOMMU bitmap needs
to have dynamic size"). I can only assume that I mistakenly took the
4.15 backport as basis and/or reference.

Fixes: fa45f6b5560e ("VT-d: split domid map cleanup check into a function")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>