ptp: Add error handling for adjfine callback in ptp_clock_adjtime

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: 39a8cbd9ca05 ("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>