audit: normalize MAC_POLICY_LOAD record

The audit MAC_POLICY_LOAD record had redundant dangling keywords and was
missing information about which LSM was responsible and its completion
status.  While this record is only issued on success, the parser expects
the res= field to be present.

Old record:
type=MAC_POLICY_LOAD msg=audit(1479299795.404:43): policy loaded auid=0 ses=1

Delete the redundant dangling keywords, add the lsm= field and the res=
field.

New record:
type=MAC_POLICY_LOAD msg=audit(1523293846.204:894): auid=0 ses=1 lsm=selinux res=1

See: https://github.com/linux-audit/audit-kernel/issues/47



Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>