[WATCHDOG] Atmel AT91RM9200 rename.

The new Atmel AT91SAM9261 and AT91SAM9260 processors use a different
internal watchdog peripheral.  This watchdog driver is therefore
AT91RM9200-specific.

This patch renames at91_wdt.c to at91rm9200_wdt.c, and changes the name
of the configuration option.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/char/watchdog/Kconfig b/drivers/char/watchdog/Kconfig
index 847a260..529f0a7 100644
--- a/drivers/char/watchdog/Kconfig
+++ b/drivers/char/watchdog/Kconfig
@@ -60,7 +60,7 @@
 
 # ARM Architecture
 
-config AT91_WATCHDOG
+config AT91RM9200_WATCHDOG
 	tristate "AT91RM9200 watchdog"
 	depends on WATCHDOG && ARCH_AT91RM9200
 	help