smsc95xx: use ethtool_op_get_ts_info()

smsc95xx: use ethtool_op_get_ts_info()

This change enables the use of SW timestamping on Raspberry PI.

smsc95xx uses the usbnet transmit function usbnet_start_xmit(), which
implements software timestamping. However the SOF_TIMESTAMPING_TX_SOFTWARE
capability was missing and only SOF_TIMESTAMPING_RX_SOFTWARE was announced.
By using ethtool_op_get_ts_info() as get_ts_info() also the
SOF_TIMESTAMPING_TX_SOFTWARE is announced.

Signed-off-by: Petr Kulhavy <[email protected]>
Reviewed-by: Woojung Huh <[email protected]>
Signed-off-by: David S. Miller <[email protected]>