Use spci_vm_id_t for VM IDs, and rename vm_get to vm_find.

This means that we consistently use _get for looking up by index, _find
for looking up by ID (even if the ID happens to be the same as the index
for now).

Change-Id: I54c958be771151316781f80e2057e3076fc4ae0c
diff --git a/src/main.c b/src/main.c
index bd4c319..e5dc7b7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -146,7 +146,7 @@
 		panic("mm_cpu_init failed");
 	}
 
-	vcpu = vm_get_vcpu(vm_get(HF_PRIMARY_VM_ID), cpu_index(c));
+	vcpu = vm_get_vcpu(vm_find(HF_PRIMARY_VM_ID), cpu_index(c));
 	vm = vcpu->vm;
 	vcpu->cpu = c;