This patch fixes the following warning raised
when compile:

WARNING: modpost: missing MODULE_LICENSE()
in drivers/net/ethernet/stmicro/stmmac/stmmac.o
Reported-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NGiuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>