net: dpaa2-eth: add trace points on XSK events

Define the dpaa2_tx_xsk_fd and dpaa2_rx_xsk_fd trace events for the XSK
zero-copy Rx and Tx path.  Also, define the dpaa2_eth_buf as an event
class so that both dpaa2_eth_buf_seed and dpaa2_xsk_buf_seed traces can
derive from the same class.

Signed-off-by: Robert-Ionut Alexa <robert-ionut.alexa@nxp.com>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>