watchdog: kempld-wdt: Use the correct value when configuring the prescaler with the watchdog

Use the prescaler index, rather than its value, to configure the watchdog.
This will prevent a mismatch with the prescaler used to calculate the cycles.
Signed-off-by: Per Gundberg <per.gundberg@icomera.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Michael Brunner <michael.brunner@kontron.com>
Tested-by: Michael Brunner <michael.brunner@kontron.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: stable <stable@vger.kernel.org>

drivers/watchdog/kempld_wdt.c

@@ -162,7 +162,7 @@ static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
 	kempld_get_mutex(pld);
 	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 	stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
-	stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
+	stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
 	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 	kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
 			stage_timeout);