northbridge/amd/agesa/family1{4,5,5tn,6kb}: Reduce differences

Lets cut down on whitespace differences, fix some typos and indents.
Also make use of ARRAY_SIZE() macro instead of a local redefinition.

Fix NULL pointer checks ordering and not to use zero.

Change-Id: I93f344d300c04570d795659d848255cb1832e1d8
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7528
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
diff --git a/src/northbridge/amd/agesa/family15tn/chip.h b/src/northbridge/amd/agesa/family15tn/chip.h
index 41571db..dafbfae 100644
--- a/src/northbridge/amd/agesa/family15tn/chip.h
+++ b/src/northbridge/amd/agesa/family15tn/chip.h
@@ -17,8 +17,8 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#ifndef _AGESA_FAM15TN_CHIP_H_
-#define _AGESA_FAM15TN_CHIP_H_
+#ifndef _NB_AGESA_CHIP_H_
+#define _NB_AGESA_CHIP_H_
 
 struct northbridge_amd_agesa_family15tn_config
 {