[MIPS] Switch from to_tm to rtc_time_to_tm

This replaces the MIPS-specific to_tm function with the generic
rtc_time_to_tm function.  The big difference between the two functions is
that rtc_time_to_tm uses epoch 70 while to_tm uses 1970, so the result of
rtc_time_to_tm needs to be fixed up.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/pmc-sierra/yosemite/setup.c b/arch/mips/pmc-sierra/yosemite/setup.c
index 56bf695..015fcc3 100644
--- a/arch/mips/pmc-sierra/yosemite/setup.c
+++ b/arch/mips/pmc-sierra/yosemite/setup.c
@@ -100,8 +100,12 @@
 	struct rtc_time tm;
 	unsigned long flags;
 
-	/* convert to a more useful format -- note months count from 0 */
-	to_tm(sec, &tm);
+	/*
+	 * Convert to a more useful format -- note months count from 0
+	 * and years from 1900
+	 */
+	rtc_time_to_tm(tim, &tm);
+	tm.tm_year += 1900;
 	tm.tm_mon += 1;
 
 	spin_lock_irqsave(&rtc_lock, flags);