uboot-imx

ARM: DTS: stm32: add stm32f429-disco-u-boot dts file

_ 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>