net: stmmac: mdio: remove reset gpio free

This patch removes gpio_free for reset line of the phy, driver stores
the gpio number in its private data-structure to use in future. As the
driver uses this pin in future this pin should not be freed.

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