net: stmmac: xgmac: show more MAC HW features in debugfs

1. Show TSSTSSEL(Timestamp System Time Source),
ADDMACADRSEL(additional MAC addresses), SMASEL(SMA/MDIO Interface),
HDSEL(Half-duplex Support) in debugfs.
2. Show exact number of additional MAC address registers for XGMAC2 core.
3. XGMAC2 core does not have different IP checksum offload types, so just
show rx_coe instead of rx_coe_type1 or rx_coe_type2.
4. XGMAC2 core does not have rxfifo_over_2048 definition, skip it.

Signed-off-by: Furong Xu <0x1207@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>