stmmac: dwmac-sti: fix broken STiD127 compatibility

This is to fix the compatibility to the STiD127 SoC.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>