lan743x: Make symbol lan743x_pm_ops static

Fixes the following sparse warning:

drivers/net/ethernet/microchip/lan743x_main.c:2944:25: warning:
 symbol 'lan743x_pm_ops' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Acked-by: NBryan Whitehead <Bryan.Whitehead@microchip.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/lan743x_main.c

@@ -2941,7 +2941,7 @@ static int lan743x_pm_resume(struct device *dev)
 	return 0;
 }
 
-const struct dev_pm_ops lan743x_pm_ops = {
+static const struct dev_pm_ops lan743x_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(lan743x_pm_suspend, lan743x_pm_resume)
 };
 #endif /*CONFIG_PM */