sfc: support rx-fcs and rx-all

Ethernet FCS inclusion (rx-fcs) is supported on EF10 NICs, conditional on
 a firmware capability bit (MC_CMD_GET_CAPABILITIES_OUT_RX_INCLUDE_FCS).
To receive frames with bad FCS (rx-all) we just don't return the discard
 flag EFX_RX_PKT_DISCARD from efx_ef10_handle_rx_event_errors() or
 efx_farch_handle_rx_not_ok().

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>