mainboard: Make use of ARRAY_SIZE in buildOpts.c on AGESA platforms

Found using coccinelle.

Change-Id: I406de6cfe25d3b471dbb6f98d9c62addae008de3
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6195
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/mainboard/amd/olivehill/buildOpts.c

@@ -33,6 +33,7 @@
  * @e \$Revision: 23714 $   @e \$Date: 2009-12-09 17:28:37 -0600 (Wed, 09 Dec 2009) $
  */
 
+#include <stdlib.h>
 #include "AGESA.h"
 //#include "CommonReturns.h"
 #include "Filecode.h"
@@ -503,4 +504,4 @@ UINT8 AGESA_MEM_TABLE_TN[][sizeof (MEM_TABLE_ALIAS)] =
  // TABLE END
   NBACCESS (MTEnd, 0,  0, 0, 0, 0),      // End of Table
 };
-UINT8 SizeOfTableTN = sizeof (AGESA_MEM_TABLE_TN) / sizeof (AGESA_MEM_TABLE_TN[0]);
+UINT8 SizeOfTableTN = ARRAY_SIZE(AGESA_MEM_TABLE_TN);