ice: restore PTP Rx timestamp config after ethtool set-channels

When ethtool -L changes queue counts, ice_vsi_recfg_qs() closes and
rebuilds the VSI, reallocating Rx rings. The newly allocated rings have
ptp_rx cleared, so RX hardware timestamps are no longer attached to skb
until hwtstamp configuration is applied again.

Restore timestamp mode after ice_vsi_open() in the queue reconfiguration
path, matching reset/rebuild behavior and ensuring newly rebuilt Rx rings
have PTP RX timestamping re-enabled.

Testing hints:
- run ptp4l application in client synchronization mode:
	 ptp4l -i ethX -m -s
- run PTP traffic
- change queue number on ethX netdev interface:
	ethtool -L ethX combined new_queue_size
- observe ptp4l output
- expected result: no "received DELAY_REQ without timestamp" messages

Fixes: 77a781155a65 ("ice: enable receive hardware timestamping")
Cc: stable@vger.kernel.org
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Grzegorz Nitka <grzegorz.nitka@intel.com>