net: stmmac: print phy information

When a PHY is found, printing which one was found (and which type/model) is
a good information to know.

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Acked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>