net: dwmac-sun8i: Use parsed internal PHY address instead of 1

While the MDIO address of the internal PHY on Allwinner sun8i chips is
generally 1, of_mdio_parse_addr is used to cleanly parse the address
from the device-tree instead of hardcoding it.

A commit reworking the code ditched the parsed value and hardcoded the
value 1 instead, which didn't really break anything but is more fragile
and not future-proof.

Restore the initial behavior using the parsed address returned from the
helper.

Fixes: 634db83b8265 ("net: stmmac: dwmac-sun8i: Handle integrated/external MDIOs")
Signed-off-by: Paul Kocialkowski <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Acked-by: Corentin LABBE <[e-mail]>
Tested-by: Corentin LABBE <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c

···
 		/* of_mdio_parse_addr returns a valid (0 ~ 31) PHY
 		 * address. No need to mask it again.
 		 */
-		reg |= 1 << H3_EPHY_ADDR_SHIFT;
+		reg |= ret << H3_EPHY_ADDR_SHIFT;
 	} else {
 		/* For SoCs without internal PHY the PHY selection bit should be
 		 * set to 0 (external PHY).