ARM: dts: STiH407-pinctrl: Add i2c2_alt2_1 node

Add missing pin muxing for I2C2 alternate 2. This
i2c2 pin muxing is dedicated for 96board high speed
expansion connector.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
[Lee: Correct spacing between nodes]
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>