rtc: pm8xxx: Return -ENODEV if set_time disallowed

Having !allow_set_time is equivalent to non-implemented set_time
function, which is normally represented with -ENODEV error in RTC
subsystem.

Today we are returning -EACCES error code, which is not considered
by RTC clients as a 'non implemented' feature, and which causes NTP
to retry hw clk sync (update_rtc) indefinitely.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1645090578-20734-1-git-send-email-loic.poulain@linaro.org

drivers/rtc/rtc-pm8xxx.c

@@ -84,7 +84,7 @@ static int pm8xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	const struct pm8xxx_rtc_regs *regs = rtc_dd->regs;
 
 	if (!rtc_dd->allow_set_time)
-		return -EACCES;
+		return -ENODEV;
 
 	secs = rtc_tm_to_time64(tm);