Implement byte reading macros to remaining files

The previous commits cherry picked from the changes made with relation
to the development branch. This commit makes the appropriate chnages to
the files not present in the development branch.

Signed-off-by: Joe Subbiani <joe.subbiani@arm.com>
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index a665ec9..28c57dc 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -494,8 +494,8 @@
 
     memcpy( header, ctr, 8 );
     header[ 8] = (unsigned char)  type;
-    header[ 9] = (unsigned char)( len >> 8 );
-    header[10] = (unsigned char)( len      );
+    header[ 9] = MBEDTLS_BYTE_1( len );
+    header[10] = MBEDTLS_BYTE_0( len );
 
     memset( padding, 0x36, padlen );
     mbedtls_md_starts( md_ctx );