MA-18192 Only bump the rollback index when avb verify ok

MA-18192 Only bump the rollback index when avb verify ok

AVB verify should fail for GKI boot image but we should allow it
continue to boot in UNLOCKED state. In such case, we should not
update the stored rollback index.

This commit will update the rollback index only when the AVB
verify is OK to prevent rollback index check error.

Test: boots.

Signed-off-by: Ji Luo <ji.luo@nxp.com>
Change-Id: I82678d288edd4df6de40a1ca863ed36d3b3658a8
(cherry picked from commit ea48b544581d630bc031a7968a90b2fcf328424a)
(cherry picked from commit 8619089859b6c24f82a2f6fda9bd2c58c2e38851)