_ Add gpio compatible and aliases for stm32f429
_ Add FMC sdram node with associated new bindings value to
manage second bank (ie bank 1).
_ Add "u-boot,dm-pre-reloc" for rcc, fmc, fixed-clock, pinctrl,
pwrcfg and gpio nodes.
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>