ARM: dts: stm32: Sync DT with v4.20 kernel for stm32h7

Synchronize stm32h7 device tree with kernel v4.20.
U-boot DT files and pinctrl bindings are updated,
useless nodes are removed and gpio compatible added.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>