iommu/vt-d: Remove misleading "domain 0" test from domain_exit()
The "Domain 0 is reserved, so dont process it" comment suggests that a NULL
pointer corresponds to domain 0. I don't think that's true, and in any
case, every caller supplies a non-NULL domain pointer that has already been
dereferenced, so the test is unnecessary.
Remove the test for a null "domain" pointer. No functional change
intended.
This null pointer check was added by
5e98c4b1d6e8 ("Allocation and free
functions of virtual machine domain").
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>