platform: msm_shared: Add changes as per AVB2.0 specs

As per the requirement of AVB2.0 current call flow aboot_init
is updated to make sure that device is booting with AVB2.0
enable.Fix kernel cmdline for recovery and add checks to verify
the boot image.

Change-Id: Icfb250eac71edf07ea6f6123ddd15c6aaaa1629f
12 files changed