boards: mimxrt1160_evk: add support for loading M4 image from OCRAM

Add support for loading M4 image from OCRAM when running with dual core
operation. The M7 core will copy the M4 image from flash into OCRAM, and
the M4 core will execute it there.

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