drivers: flash_mcux_flexspi_nor: Move all device data to RAM

Move all device data to RAM. Since the flexspi driver accesses the
flash device that is being used for XIP, various RWW hazards can occur
if the flexspi driver is interacting with the flash device, while
running in XIP mode.

Fixes #45182

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>