[REFACTOR] Hafnium style: capitalize CPU, vCPU, and VM.

Change-Id: I6090deee0f52737653f5b18c09a1c64cadd38c8c
diff --git a/src/spci_architected_message.c b/src/spci_architected_message.c
index d427cd2..c17daf4 100644
--- a/src/spci_architected_message.c
+++ b/src/spci_architected_message.c
@@ -350,7 +350,7 @@
 static bool clear_memory(paddr_t begin, paddr_t end, struct mpool *ppool)
 {
 	/*
-	 * TODO: change this to a cpu local single page window rather than a
+	 * TODO: change this to a CPU local single page window rather than a
 	 *       global mapping of the whole range. Such an approach will limit
 	 *       the changes to stage-1 tables and will allow only local
 	 *       invalidation.