MFC r271700: Fix typo in defined ROD types in r269497.

Approved by:	re (gjb)
MFC r271702:
Fix tpc_create_token() introduced in r269497 to encode CREATOR LOGICAL
UNIT DESCRIPTOR field as Identification Descriptor CSCD descriptor, not
just as Identification Descriptor.

Approved by:	re (gjb)
MFC r271716:
Presence of any VM_PROT bits in the permission argument on x86 implies
that the entry is readable and valid.

Approved by:	re (gjb)