audit: remove unused actx param from audit_rule_match

The audit_rule_match() struct audit_context *actx parameter is not used
by any in-tree consumers (selinux, apparmour, integrity, smack).

The audit context is an internal audit structure that should only be
accessed by audit accessor functions.

It was part of commit 03d37d25e0 ("LSM/Audit: Introduce generic
Audit LSM hooks") but appears to have never been used.

Remove it.

Please see the github issue
https://github.com/linux-audit/audit-kernel/issues/107

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: fixed the referenced commit title]
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/integrity/ima/ima_policy.c

@@ -340,8 +340,7 @@ retry:
 			rc = security_filter_rule_match(osid,
 							rule->lsm[i].type,
 							Audit_equal,
-							rule->lsm[i].rule,
-							NULL);
+							rule->lsm[i].rule);
 			break;
 		case LSM_SUBJ_USER:
 		case LSM_SUBJ_ROLE:
@@ -349,8 +348,7 @@ retry:
 			rc = security_filter_rule_match(secid,
 							rule->lsm[i].type,
 							Audit_equal,
-							rule->lsm[i].rule,
-							NULL);
+							rule->lsm[i].rule);
 		default:
 			break;
 		}