Extract container_of definition out of individual bindings

This will make possible reuse this portion on code in the future.

Testing: no change in functionality; compiles successfuly

Signed-off-by: Przemyslaw Czarnowski <przemyslaw.hawrylewicz.czarnowski@intel.com>
Change-Id: Ie92161c547e275d9aa00d643d8d4879d2f5dd199
diff --git a/tests/test-utils.h b/tests/test-utils.h
index e8c74f1..4b000e1 100644
--- a/tests/test-utils.h
+++ b/tests/test-utils.h
@@ -4,11 +4,7 @@
 #define _MCTP_TESTS_TEST_UTILS_H
 
 #include <libmctp.h>
-
-#ifndef container_of
-#define container_of(ptr, type, member) \
-    (type *)((char *)(ptr) - (char *)&((type *)0)->member)
-#endif
+#include <container_of.h>
 
 /* test binding implementation */
 
diff --git a/tests/test_astlpc.c b/tests/test_astlpc.c
index efa38ab..2d637de 100644
--- a/tests/test_astlpc.c
+++ b/tests/test_astlpc.c
@@ -6,6 +6,7 @@
 
 #include "libmctp-astlpc.h"
 #include "libmctp-log.h"
+#include "container_of.h"
 
 #ifdef NDEBUG
 #undef NDEBUG
@@ -58,11 +59,6 @@
 	uint8_t *lpc;
 };
 
-#ifndef container_of
-#define container_of(ptr, type, member) \
-	(type *)((char *)(ptr) - (char *)&((type *)0)->member)
-#endif
-
 #define binding_to_mmio(b) \
 	container_of(b, struct mctp_binding_astlpc_mmio, astlpc)