Using SPCI memory sharing functions rather than MSG_SEND.

Bug: 132420445
Change-Id: I1d29ebfdf179c7a7c07223f8c027c22c055d333a
diff --git a/src/spci_architected_message.c b/src/spci_architected_message.c
index 06106d5..9d9c6c0 100644
--- a/src/spci_architected_message.c
+++ b/src/spci_architected_message.c
@@ -595,7 +595,7 @@
 
 	/* We only support a single recipient. */
 	if (memory_region->attribute_count != 1) {
-		return spci_error(SPCI_INVALID_PARAMETERS);
+		return spci_error(SPCI_NOT_SUPPORTED);
 	}
 
 	/* The recipient must match the message recipient. */