ARM change name of defines for AT91 arm926ejs

Configuration defines should be preceeded with CONFIG_SYS_. Renamed
some at91 specific defines to conform to this naming convention:

AT91_CPU_NAME to CONFIG_SYS_AT91_CPU_NAME
AT91_MAIN_CLOCK to CONFIG_SYS_AT91_MAIN_CLOCK

Signed-off-by: Achim Ehrlich <aehrlich@taskit.de>
diff --git a/include/configs/cpu9260.h b/include/configs/cpu9260.h
index 38f34c2..fb6f79a 100644
--- a/include/configs/cpu9260.h
+++ b/include/configs/cpu9260.h
@@ -35,7 +35,7 @@
 
 #define CONFIG_DISPLAY_CPUINFO	1
 
-#define AT91_MAIN_CLOCK		18432000
+#define CONFIG_SYS_AT91_MAIN_CLOCK	18432000
 #define CONFIG_SYS_HZ		1000
 
 #define CONFIG_ARM926EJS	1