gve: Move ptp_schedule_worker to gve_init_clock

gve: Move ptp_schedule_worker to gve_init_clock

Previously, gve had been only initializing ptp aux work when
hardware timestamping was initialized through ndo_hwtsatmp_set. As this
patch series introduces XDP hardware timestamp metadata which will
require the ptp aux work, the work can't be gated on the
kernel_hwtstamp_config being set and must be initialized elsewhere.

For simplicity, ptp_schedule_worker is invoked right after the ptp_clock
is registered with the kernel (which happens during gve_probe or
following reset). The worker is scheduled in GVE_NIC_TS_SYNC_INTERVAL_MS
as the synchronous call to gve_clock_nic_ts_read makes the worker
redundant if scheduled immediately.

If gve cannot read the device clock immediately, it errors out of
gve_init_clock.

Signed-off-by: Tim Hostetler <thostet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
Link: https://patch.msgid.link/20251114211146.292068-2-joshwash@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>