sfc: Simplify XMAC link polling

From: Steve Hodgson <shodgson@solarflare.com>

Only the XMAC on Falcon needs help from the driver to poll and reset
the MAC-PHY link (XAUI); GMII is a simple parallel bus and on later
NICs firmware takes care of the XAUI link.  Also, an XMAC interrupt
currently schedules a work item which simply clears a flag
(efx_nic::mac_up) to be checked by the regular monitor (or the next
link reconfiguration, if that is sooner).

Rename the flag to xmac_poll_required, changing its sense.  Remove the
needless indirection and just set the flag immediately.  Call
falcon_xmac_poll() directly where required.

Add a new generic operation mac_op::check_fault to check the link
outside of regular monitoring, as required during self-tests.

(Note that this leaves us with an unused work item, but we will
immediately have another use for it.)

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/falcon_gmac.c b/drivers/net/sfc/falcon_gmac.c
index 2aeb3fc..66d499c 100644
--- a/drivers/net/sfc/falcon_gmac.c
+++ b/drivers/net/sfc/falcon_gmac.c
@@ -216,9 +216,13 @@
 	mac_stats->rx_lt64 = mac_stats->rx_good_lt64 + mac_stats->rx_bad_lt64;
 }
 
+static bool falcon_gmac_check_fault(struct efx_nic *efx)
+{
+	return false;
+}
+
 struct efx_mac_operations falcon_gmac_operations = {
 	.reconfigure	= falcon_reconfigure_gmac,
 	.update_stats	= falcon_update_stats_gmac,
-	.irq		= efx_port_dummy_op_void,
-	.poll		= efx_port_dummy_op_void,
+	.check_fault 	= falcon_gmac_check_fault,
 };