eth: fbnic: add support for TMI stats

eth: fbnic: add support for TMI stats

This patch add coverage for TMI stats including PTP stats and drop
stats.

PTP stats include illegal requests, bad timestamp and good timestamps.
The bad timestamp and illegal request counters are reported under as
`error` via `ethtool -T` Both these counters are individually being
reported via `ethtool -S`

The good timestamp stats are being reported as `pkts` via `ethtool -T`

ethtool -S eth0 | grep "ptp"
     ptp_illegal_req: 0
     ptp_good_ts: 0
     ptp_bad_ts: 0

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250410070859.4160768-5-mohsin.bashr@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>