mx6: Enable L2 cache support

Add L2 cache support and enable it by default.

Configure the L2 cache in the same way as done by FSL kernel:
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/arch/arm/mach-mx6/mm.c?h=imx_3.0.35_4.1.0

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Dirk Behme <dirk.behme@gmail.com>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/include/configs/mx6_common.h b/include/configs/mx6_common.h
index 514d634..eb107d3 100644
--- a/include/configs/mx6_common.h
+++ b/include/configs/mx6_common.h
@@ -22,4 +22,9 @@
 #define CONFIG_ARM_ERRATA_751472
 #define CONFIG_BOARD_POSTCLK_INIT
 
+#ifndef CONFIG_SYS_L2CACHE_OFF
+#define CONFIG_SYS_L2_PL310
+#define CONFIG_SYS_PL310_BASE	L2_PL310_BASE
+#endif
+
 #endif