feat(bl): add interface to query TF-A semantic ver

Adding interface for stand-alone semantic version of TF-A
for exporting to RSS attestation, and potentially other areas
as well.

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: Ib4a2c47aa1e42a3b850185e674c90708a05cda53
diff --git a/common/bl_common.c b/common/bl_common.c
index 9bfaafd..8fce02f 100644
--- a/common/bl_common.c
+++ b/common/bl_common.c
@@ -269,3 +269,12 @@
 #endif
 #undef PRINT_IMAGE_ARG
 }
+
+/*
+ * This function is for returning the TF-A version
+ */
+const char *get_version(void)
+{
+	extern const char version[];
+	return version;
+}