dts: arm: stm32h72x and h73x have octospi peripherals

Add the octospi nodes to the stm32h723/h725
and h730/h733/h735 devices.
Note that RM0468 gives a size of 1kB.
The definition of the octospi clock source for both intances
is given by the DTS node. The selected value for
the alternate clock control is the PLL1_Q.

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