stv0991: enable ethernet support

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
diff --git a/arch/arm/include/asm/arch-stv0991/stv0991_periph.h b/arch/arm/include/asm/arch-stv0991/stv0991_periph.h
index f723771..f728c83 100644
--- a/arch/arm/include/asm/arch-stv0991/stv0991_periph.h
+++ b/arch/arm/include/asm/arch-stv0991/stv0991_periph.h
@@ -17,6 +17,7 @@
 enum periph_id {
 	UART_GPIOC_30_31 = 0,
 	UART_GPIOB_16_17,
+	ETH_GPIOB_10_31_C_0_4,
 	PERIPH_ID_I2C0,
 	PERIPH_ID_I2C1,
 	PERIPH_ID_I2C2,