soc: st: stm32: Use flash-controller to detect running from external flash

Use the zephyr,flash-controller node and the respective compatible
'st,stm32-xspi-nor' to detect if the device is running from external
flash, instead of assuming that the parent node of the flash is the
SPI controller. This fixes an issue when soc-nv-flash is used as the
zephyr,flash node.

Signed-off-by: Tim Pambor <tim.pambor@codewrights.de>
1 file changed