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/load.c b/src/load.c
index c1da513..41c417c 100644
--- a/src/load.c
+++ b/src/load.c
@@ -267,7 +267,7 @@
 	memcpy_s(mem_ranges_available, sizeof(mem_ranges_available),
 		 params->mem_ranges, sizeof(params->mem_ranges));
 
-	primary = vm_get(HF_PRIMARY_VM_ID);
+	primary = vm_find(HF_PRIMARY_VM_ID);
 
 	if (!find_file(cpio, "vms.txt", &it)) {
 		dlog("vms.txt is missing\n");