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/board/atmel/at91cap9adk/at91cap9adk.c b/board/atmel/at91cap9adk/at91cap9adk.c
index 9f73df6..258d1ea 100644
--- a/board/atmel/at91cap9adk/at91cap9adk.c
+++ b/board/atmel/at91cap9adk/at91cap9adk.c
@@ -282,7 +282,7 @@
 	lcd_printf ("(C) 2008 ATMEL Corp\n");
 	lcd_printf ("at91support@atmel.com\n");
 	lcd_printf ("%s CPU at %s MHz\n",
-		AT91_CPU_NAME,
+		CONFIG_SYS_AT91_CPU_NAME,
 		strmhz(temp, get_cpu_clk_rate()));
 
 	dram_size = 0;