boards: arm: Add mcuboot flash partitions to mimxrt1024_evk

Adds flash partitions and chosen nodes to the mimxrt1024_evk device tree
to support mcuboot on the internal QSPI flash.

Also adds missing zephyr,itcm chosen node.

Also enables FlexSPI flash driver XIP mode support on this board to
support mcuboot.

Signed-off-by: Mikkel Jakobsen <mikkel.aunsbjerg@prevas.dk>