AGESA: Add agesa_helper.h header

These definitions do not require AGESA.h include,
and we will eventually remove agesawrapper.h files.

Change-Id: I1b5b78409828aaf2616e177bb54a054960c3869f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/18588
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/northbridge/amd/agesa/family15tn/northbridge.c b/src/northbridge/amd/agesa/family15tn/northbridge.c
index 2f05334..c8909fb 100644
--- a/src/northbridge/amd/agesa/family15tn/northbridge.c
+++ b/src/northbridge/amd/agesa/family15tn/northbridge.c
@@ -37,7 +37,9 @@
 #include <Topology.h>
 #include <cpu/amd/amdfam15.h>
 #include <cpuRegisters.h>
+
 #include <northbridge/amd/agesa/agesawrapper.h>
+#include <northbridge/amd/agesa/agesa_helper.h>
 
 #define MAX_NODE_NUMS (MAX_NODES * MAX_DIES)