boards: arm: stm32h735g disco target board has octo SPI instance

This commit enables the octo SPI peripheral to the flash-nor
on the target board stm32h735g_disco from STMicroelectronics.
The octospi1 is connected to the NOR- octo-flash through
the OSPI IO Manager.
Note that JESD16 requires 9 dwords for the sdfp table.
The NOR octoflash is MX25LM51245 or compatible.

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