arm920t/at91: use new clock.c features

This patch enables the new clock features from arm920t/at91/clock.c. This
is an required step to get at91rm9200_usart replaced by atmel_usart driver.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
Cc: Jens Scharsig <js_at_ng@scharsoft.de>
Cc: Eric Bénard <eric@eukrea.com>
diff --git a/include/configs/at91rm9200ek.h b/include/configs/at91rm9200ek.h
index 16cd214..ee199ab 100644
--- a/include/configs/at91rm9200ek.h
+++ b/include/configs/at91rm9200ek.h
@@ -55,6 +55,7 @@
  * CONFIG_SYS_HZ is the tick rate for timer tc0
  */
 #define AT91C_XTAL_CLOCK		18432000
+#define CONFIG_SYS_AT91_SLOW_CLOCK	32768
 #define AT91C_MAIN_CLOCK		((AT91C_XTAL_CLOCK / 4) * 39)
 #define AT91C_MASTER_CLOCK		(AT91C_MAIN_CLOCK / 3 )
 #define CONFIG_SYS_HZ_CLOCK		(AT91C_MASTER_CLOCK / 2)
@@ -66,6 +67,8 @@
 #define CONFIG_CPUAT91
 #define USE_920T_MMU
 
+#include <asm/hardware.h>	/* needed for port definitions */
+
 #define CONFIG_CMDLINE_TAG
 #define CONFIG_SETUP_MEMORY_TAGS
 #define CONFIG_INITRD_TAG