bnxt_en: convert to ndo_hwtstamp_get() and ndo_hwtstamp_set()

Convert bnxt dirver to use new timestamping configuration API.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20250923173310.139623-3-vadim.fedorenko@linux.dev


Signed-off-by: Jakub Kicinski <kuba@kernel.org>