ptp: Add error handling for adjfine callback in ptp_clock_adjtime

ptp_clock_adjtime sets ptp->dialed_frequency even when adjfine
callback returns an error. This causes subsequent reads to return
an incorrect value.

Fix this by adding error check before ptp->dialed_frequency is set.

Fixes: 39a8cbd ("ptp: remember the adjusted frequency")
Signed-off-by: Ajay Kaher <ajay.kaher@broadcom.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://patch.msgid.link/20241125105954.1509971-1-ajay.kaher@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: akaher

drivers/ptp/ptp_clock.c

@@ -150,7 +150,8 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
 		if (ppb > ops->max_adj || ppb < -ops->max_adj)
 			return -ERANGE;
 		err = ops->adjfine(ops, tx->freq);
-		ptp->dialed_frequency = tx->freq;
+		if (!err)
+			ptp->dialed_frequency = tx->freq;
 	} else if (tx->modes & ADJ_OFFSET) {
 		if (ops->adjphase) {
 			s32 max_phase_adj = ops->getmaxphase(ops);