adb: early-mount: fix verity toggle through adb for early mount

verity toggle through adb failed to work for early mount due to fstab
entries being moved into kernel/dt. This change fixes that by using the
new fs_mgr_read_fstab_default() api that will make sure all fstab
entries (from dt as well as from /fstab.{ro.hardware}) are combined
before returning the fstab object.

b/27805372

Test: early mount /system and /vendor on angler.
- test adb disable-verity && adb root to ensure rebooted instance
doesn't have 'partition.system.verified' property set. i.e. verity is
indeed disabled.

- test adb enable-verity && adb root to ensure rebooted instance does
have 'partition.system.verified' property set, i.e. verity is enabled.
also verified by trying to do 'adb remount' which correctly warns about
verity

Change-Id: Iffdcc0a0b959a65c326219bd4e9e41cba9ec7c88
Signed-off-by: Sandeep Patil <sspatil@google.com>
1 file changed