ptp: ocp: Add .getmaxphase ptp_clock_info callback

Add a function that advertises a maximum offset of zero supported by
ptp_clock_info .adjphase in the OCP null ptp implementation.

Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jonathan Lemon <jonathan.lemon@gmail.com>
Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_ocp.c

@@ -1124,6 +1124,12 @@ ptp_ocp_null_adjfine(struct ptp_clock_info *ptp_info, long scaled_ppm)
 	return -EOPNOTSUPP;
 }
 
+static s32
+ptp_ocp_null_getmaxphase(struct ptp_clock_info *ptp_info)
+{
+	return 0;
+}
+
 static int
 ptp_ocp_null_adjphase(struct ptp_clock_info *ptp_info, s32 phase_ns)
 {
@@ -1239,6 +1245,7 @@ static const struct ptp_clock_info ptp_ocp_clock_info = {
 	.adjtime	= ptp_ocp_adjtime,
 	.adjfine	= ptp_ocp_null_adjfine,
 	.adjphase	= ptp_ocp_null_adjphase,
+	.getmaxphase	= ptp_ocp_null_getmaxphase,
 	.enable		= ptp_ocp_enable,
 	.verify		= ptp_ocp_verify,
 	.pps		= true,