rtc: at91sam9: remove duplicate assignment of variable mr

mr is written twice with the same value, remove one of the
redundant assignments to mr.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-at91sam9.c

@@ -268,7 +268,7 @@ static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 {
 	struct sam9_rtc *rtc = dev_get_drvdata(dev);
-	u32 mr = mr = rtt_readl(rtc, MR);
+	u32 mr = rtt_readl(rtc, MR);
 
 	seq_printf(seq, "update_IRQ\t: %s\n",
 			(mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");