nios2: Use read_persistent_clock64() instead of read_persistent_clock()

Since struct timespec is not y2038 safe on 32bit machines, this patch
converts read_persistent_clock() to read_persistent_clock64() using
struct timespec64, as well as converting mktime() to mktime64().
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>

arch/nios2/kernel/time.c

@@ -336,9 +336,9 @@ static int __init nios2_time_init(struct device_node *timer)
 	return ret;
 }
 
-void read_persistent_clock(struct timespec *ts)
+void read_persistent_clock64(struct timespec64 *ts)
 {
-	ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
+	ts->tv_sec = mktime64(2007, 1, 1, 0, 0, 0);
 	ts->tv_nsec = 0;
 }