dts: arm: stm32 devices with octospi is named spi node

Fixes the CMake Warning on build/zephyr/zephyr.dts:
Warning (spi_bus_bridge): /soc/octospi@52005000: node name
for SPI buses should be 'spi'
<stdout>: Warning (spi_bus_reg): Failed prerequisite 'spi_bus_bridge'

Signed-off-by: Francois Ramu <francois.ramu@st.com>