stmmac: fix phy naming inconsistency

stmmac: fix phy naming inconsistency

After commit "db8857b stmmac: use an unique MDIO bus name" my
device stopped being probed because two different names were being
used in different places. This fixes the inconsistency.

Signed-off-by: Alessandro Rubini <[email protected]>
Acked-by: Giancarlo Asnaghi <[email protected]>
Cc: Giuseppe Cavallaro <[email protected]>
Cc: Florian Fainelli <[email protected]>
Acked-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>