rtc: interface: use timeu64_t for range_max

For rtc drivers where rtc->range_max is set U64_MAX, like the PS3 rtc,
rtc_valid_range() always returns -ERANGE. This is because the local
variable range_max has type time64_t, so the test
	if (time < range_min || time > range_max)
		return -ERANGE;
becomes (time < range_min || time > -1), which always evaluates to true.
timeu64_t should be used, since it's the type of rtc->range_max.
Signed-off-by: Emmanuel Nicolet <emmanuel.nicolet@gmail.com>
Link: https://lore.kernel.org/r/20190927110446.GA6289@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/interface.c

@@ -70,7 +70,7 @@ static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
 		time64_t time = rtc_tm_to_time64(tm);
 		time64_t range_min = rtc->set_start_time ? rtc->start_secs :
 			rtc->range_min;
-		time64_t range_max = rtc->set_start_time ?
+		timeu64_t range_max = rtc->set_start_time ?
 			(rtc->start_secs + rtc->range_max - rtc->range_min) :
 			rtc->range_max;