MA-14916-8 [iot] Set power-on write protection for boot1 partition

MA-14916-8 [iot] Set power-on write protection for boot1 partition

The RPMB keyslot is stored in last block of boot1 partition which
is easily erased or tampered, set power-on write protection for this
partition to prevent corruption.

Test: Power-on write protection works as expected on imx8m.

Change-Id: Ib7e1094b979f7d94c0a2817391c5b3b5f3205d76
Signed-off-by: Luo Ji <ji.luo@nxp.com>
(cherry picked from commit c7e207fbbcd8618d29b1192829c630777fea5220)
(cherry picked from commit 1bbf98ec8a550e4027f399f18781245c9faefc8e)