drivers/rtc/rtc-ds1286.c: fix compiler warning while doing make W=1

below is the warning reported with the gcc (gcc (GCC) 4.7.2 20121109
(Red Hat 4.7.2-8)) with make W=1:

  drivers/rtc/rtc-ds1286.c: In function `ds1286_read_alarm':
  drivers/rtc/rtc-ds1286.c:273:16: warning: variable `cmd' set but not used [-Wunused-but-set-variable]

fixed by removing the variable
Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-ds1286.c

@@ -270,7 +270,6 @@ static int ds1286_set_time(struct device *dev, struct rtc_time *tm)
 static int ds1286_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 {
 	struct ds1286_priv *priv = dev_get_drvdata(dev);
-	unsigned char cmd;
 	unsigned long flags;
 
 	/*
@@ -281,7 +280,7 @@ static int ds1286_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 	alm->time.tm_min = ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x7f;
 	alm->time.tm_hour = ds1286_rtc_read(priv, RTC_HOURS_ALARM)  & 0x1f;
 	alm->time.tm_wday = ds1286_rtc_read(priv, RTC_DAY_ALARM)    & 0x07;
-	cmd = ds1286_rtc_read(priv, RTC_CMD);
+	ds1286_rtc_read(priv, RTC_CMD);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	alm->time.tm_min = bcd2bin(alm->time.tm_min);