ipfilter: Locking sysctls here is not required

Locking of data structures touched by sysctls is more finely locked
in ipflter therefore higher level locks are redundant.

MFC after:	3 days

sys/contrib/ipfilter/netinet/mlfk_ipl.c

@@ -349,7 +349,6 @@ sysctl_ipf_int ( SYSCTL_HANDLER_ARGS )
 {
 	int error = 0;
 
-	WRITE_ENTER(&V_ipfmain.ipf_mutex);
 	if (arg1)
 		error = SYSCTL_OUT(req, arg1, sizeof(int));
 	else
@@ -368,7 +367,6 @@ sysctl_ipf_int ( SYSCTL_HANDLER_ARGS )
 	}
 
 sysctl_error:
-	RWLOCK_EXIT(&V_ipfmain.ipf_mutex);
 	return (error);
 }