uboot-phytec

ARM: DT: stm32f7: add gpio device tree nodes

Also created alias for gpios for stm32f7 discovery board. Based on these
aliases, it would be possible to get gpio devices by sequence.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
cc: Christophe KERELLO <christophe.kerello@st.com>