armv7: rename cache related CONFIG flags

Replace the cache related CONFIG flags with more meaningful
names. Following are the changes:

CONFIG_L2_OFF	     -> CONFIG_SYS_L2CACHE_OFF
CONFIG_SYS_NO_ICACHE -> CONFIG_SYS_ICACHE_OFF
CONFIG_SYS_NO_DCACHE -> CONFIG_SYS_DCACHE_OFF

Signed-off-by: Aneesh V <aneesh@ti.com>
V2:
 * Changed CONFIG_L2_OFF -> CONFIG_SYS_NO_L2CACHE
V4:
 * Changed all three flags to the final names suggested as above
   and accordingly changed the commit message
diff --git a/include/configs/mx51evk.h b/include/configs/mx51evk.h
index 207b20c..fd42afc 100644
--- a/include/configs/mx51evk.h
+++ b/include/configs/mx51evk.h
@@ -35,7 +35,7 @@
 
 #define CONFIG_SYS_TEXT_BASE	0x97800000
 
-#define CONFIG_L2_OFF
+#define CONFIG_SYS_L2CACHE_OFF
 
 #include <asm/arch/imx-regs.h>
 /*