bnxt_en: replace PTP spinlock with seqlock

bnxt_en: replace PTP spinlock with seqlock

We can see high contention on ptp_lock while doing RX timestamping
on high packet rates over several queues. Spinlock is not effecient
to protect timecounter for RX timestamps when reads are the most
usual operations and writes are only occasional. It's better to use
seqlock in such cases.

Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
Link: https://patch.msgid.link/20241103215108.557531-2-vadfed@meta.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>