Remove MM_MODE_STAGE1.

This doesn't belong in the modes and wasn't being used directly outside
of mm.c, where the uses are migrated over to an internal flag. The
memory management functions are now split into two, those for VM page
table, i.e. stage-2, and those for the hypervisor's own page tables,
i.e. stage-1.

Change-Id: Ib84736a905981c151a9279dac5089956d7d9ed85
diff --git a/src/vm.c b/src/vm.c
index 4a1d9d7..4a14eae 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -42,7 +42,7 @@
 	vm->vcpu_count = vcpu_count;
 	vm->mailbox.state = mailbox_state_empty;
 
-	if (!mm_ptable_init(&vm->ptable, 0, ppool)) {
+	if (!mm_vm_init(&vm->ptable, ppool)) {
 		return false;
 	}