net: gptp: Fix sync_receipt_time calculation in gptp_mi

Fix #42800
Both pss->rate_ratio and port_ds->neighbor_rate_ratio are double type
but sync_receipt_time is uint64_t. If pss->rate_ratio is less than 1
or sync_receipt_time * port_ds->neighbor_rate_ratio is less than 1,
sync_receipt_time becomes 0 due to double to uint64_t cast.
Assign port_ds->neighbor_prop_delay to sync_receipt_time first to fix
this issue.

Signed-off-by: Lu Ding <lucasdinglu@gmail.com>