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/afeb9260.h b/include/configs/afeb9260.h
index 9f8c567..24484fd 100644
--- a/include/configs/afeb9260.h
+++ b/include/configs/afeb9260.h
@@ -29,7 +29,7 @@
 #define CONFIG_AT91_LEGACY
 
 /* ARM asynchronous clock */
-#define AT91_MAIN_CLOCK		18429952	/* from 18.432 MHz crystal */
+#define CONFIG_SYS_AT91_MAIN_CLOCK		18429952	/* from 18.432 MHz crystal */
 #define CONFIG_SYS_HZ		1000
 
 #define CONFIG_AT91SAM9260	1	/* It's an Atmel AT91SAM9260 SoC*/