Is your enhancement proposal related to a problem? Please describe.
ST kit b_u585i_iot02a has flash MX25LM51245GXDI005 connected to the OCTOSPI2. I was not able to find any support for Octo-SPI. Currently kit's external flash can not be used.

Describe the solution you'd like
Add ST Octo-SPI support to the Zephyr.

Describe alternatives you've considered
If Octo-SPI can be used as SPI (MISO/MOSI) then example configuration for MX25LM51245GXDI005 would be nice.

Additional context
Add any other context or graphics (drag-and-drop an image) about the feature request here.