NET: designware: fix clock enable

After commit ba1f9667 ("net: designware: add clock support")
we got NET broken on axs101 and axs103 platforms.

Some clock don't support gating so their clock drivers don't
implement .enable/.disable callbacks. In such case clk_enable
returns -ENOSYS.
Also some clock drivers implement .enable/.disable callbacks not for all
clock IDs and return -ENOSYS (or -ENOTSUPP) for others.

If we have such clock in 'clocks' list of designware ethernet controller
node we fail to probe designware ethernet.

Fix it.
Signed-off-by: NEugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: NPatrice Chotard <patrice.chotard@st.com>
Acked-by: NJoe Hershberger <joe.hershberger@ni.com>
Reviewed-by: NPhilipp Tomsich <philipp.tomsich@theobroma-systems.com>

drivers/net/designware.c

@@ -684,7 +684,7 @@ int designware_eth_probe(struct udevice *dev)
 				break;
 
 			err = clk_enable(&priv->clocks[i]);
-			if (err) {
+			if (err && err != -ENOSYS && err != -ENOTSUPP) {
 				pr_err("failed to enable clock %d\n", i);
 				clk_free(&priv->clocks[i]);
 				goto clk_err;