Do not reboot with commit failure when ext4 userdata is wiped

When userdata partition is the type of ext4, checkpoint and metadata
encryption are enabled, boot up the images, if the slot currently
in use is not marked as "successful" and userdata is wiped, a reboot
will be triggered because of "Checkpoint commit failed"

In this patch, do not create checkpoint when the preceding condition
occurs, otherwise "dm-default-key" sits below "dm-bow".

Because cp_needsCheckpoint(), cp_prepareCheckpoint() and cp_commitChanges()
are always executed when the system boots up, and now there is a condition
that BOW device is not created while the slot in use is not marked as
"successful", set "isBow" to be "false" if BOW state fails to be set to
1, if "isBow" is false, then there is no need to commit the checkpoint,
and the system won't automatically reboot.

Bug: 193457319
Test: i.MX 8M Plus EVK, images flashed to board, misc and userdata
      partitions are wiped, checkpoint and metadata encryption are
      enabled for ext4 userdata partition.
Signed-off-by: faqiang.zhu <faqiang.zhu@nxp.com>
Change-Id: I4ad47a9504f1be0407f0fd196001a0e96919be33