Separate mm initialization from enablement.

The configuration is static so it doesn't matter where it is originally
calculated. There were previously multiple paths for enablement, one
being implicit in initialization, so this splits them apart.

Bug: 139269163
Change-Id: Ic82c351b6e84b7d46e79f5886b39d07e53e6fde6
diff --git a/src/mm.c b/src/mm.c
index 995e77d..886779f 100644
--- a/src/mm.c
+++ b/src/mm.c
@@ -950,10 +950,10 @@
 	mm_identity_map(stage1_locked, layout_data_begin(), layout_data_end(),
 			MM_MODE_R | MM_MODE_W, ppool);
 
-	return arch_mm_init(ptable.root, true);
+	return arch_mm_init();
 }
 
-bool mm_cpu_init(void)
+void mm_cpu_init(void)
 {
-	return arch_mm_init(ptable.root, false);
+	arch_mm_enable(ptable.root);
 }