net: lan966x: make reset optional

There is no dedicated reset for just the switch core. The reset which
is used up until now, is more of a global reset, resetting almost the
whole SoC and cause spurious errors by doing so. Make it possible to
handle the reset elsewhere and make the reset optional.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/lan966x/lan966x_main.c

@@ -971,7 +971,8 @@ static int lan966x_reset_switch(struct lan966x *lan966x)
 	int val = 0;
 	int ret;
 
-	switch_reset = devm_reset_control_get_shared(lan966x->dev, "switch");
+	switch_reset = devm_reset_control_get_optional_shared(lan966x->dev,
+							      "switch");
 	if (IS_ERR(switch_reset))
 		return dev_err_probe(lan966x->dev, PTR_ERR(switch_reset),
 				     "Could not obtain switch reset");