[ARM] 5390/1: AT91: Watchdog fixes

The recently merged AT91SAM9 watchdog driver uses the
AT91SAM9X_WATCHDOG config variable, whereas the original version of
the driver (and the platform support code) used AT91SAM9_WATCHDOG.
This causes the watchdog platform_device to never be registered, and
therefore the driver not to be initialized.

This patch:
- updates the platform support code to use AT91SAM9X_WATCHDOG.
- includes <linux/io.h> to fix compile error (same fix as was applied
to at91rm9200_wdt.c)
- fixes comment regarding watchdog clock-rates in at91rm9200.

Signed-off-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/watchdog/at91rm9200_wdt.c b/drivers/watchdog/at91rm9200_wdt.c
index 5531691..e35d545 100644
--- a/drivers/watchdog/at91rm9200_wdt.c
+++ b/drivers/watchdog/at91rm9200_wdt.c
@@ -107,10 +107,10 @@
 static int at91_wdt_settimeout(int new_time)
 {
 	/*
-	 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
+	 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 	 *
 	 * Since WDV is a 16-bit counter, the maximum period is
-	 * 65536 / 0.256 = 256 seconds.
+	 * 65536 / 256 = 256 seconds.
 	 */
 	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 		return -EINVAL;