sfc: Remove redundant function efx_nic_has_mc()

This function is now used in only one place, where it always returns
true.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/siena.c b/drivers/net/ethernet/sfc/siena.c
index 7bea790..9f8d7ce 100644
--- a/drivers/net/ethernet/sfc/siena.c
+++ b/drivers/net/ethernet/sfc/siena.c
@@ -409,8 +409,7 @@
 	siena_reset_hw(efx, RESET_TYPE_ALL);
 
 	/* Relinquish the device back to the BMC */
-	if (efx_nic_has_mc(efx))
-		efx_mcdi_drv_attach(efx, false, NULL);
+	efx_mcdi_drv_attach(efx, false, NULL);
 
 	/* Tear down the private nic state */
 	kfree(efx->nic_data);