sfc: get timer configuration from adapter

On SFN8000 series adapters the MC provides a method to get the timer
quantum and the maximum timer setting. We revert to the old values if the
new call is unavailable.

Signed-off-by: Bert Kenward <bkenward@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/siena.c

@@ -227,6 +227,9 @@ static int siena_probe_nvconfig(struct efx_nic *efx)
 	efx->timer_quantum_ns =
 		(caps & (1 << MC_CMD_CAPABILITIES_TURBO_ACTIVE_LBN)) ?
 		3072 : 6144; /* 768 cycles */
+	efx->timer_max_ns = efx->type->timer_period_max *
+			    efx->timer_quantum_ns;
+
 	return rc;
 }