boards: arm: mimxrt595_evk_cm33: update write alignment and partition size

Update write alignment requirements and partition sizes for RT595 EVK.
Now that MCUBoot supports 16 byte alignment, the 1 byte write mode
is no longer neccesary for the RT595. Partition sizes have been
reduced, as MCUBoot swap times are otherwise abnormally long.

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