arch: arm: mmu: generate mmu region entry from devicetree

Many peripherals have multiple instances, whether each of them
are enabled are not known. Adding all available instances into
"mmu_regions" array may not be the best choice.
This commit adds a macro to generate mmu region entry in "mmu_regions"
from devicetree. Used with "DT_FOREACH_STATUS_OKAY_VARGS", it generates
mmu region entry for all nodes enabled and compatiable to a certain
driver.

Signed-off-by: Chekhov Ma <chekhov.ma@nxp.com>