device-mapper: Add dm-bow

device-mapper: Add dm-bow

dm-bow is a device mapper driver that allows to create a checkpoint on
the volume so that it is possible to restore the state if necessary.
This is needed to protect the ext4 partition during a system upgrade in
case of a power failure.

Change-Id: Ic62e83dc5b04cfa250d1b7eaa3721546782e88eb
Originally-by: Paul Lawrence <paullawrence@google.com>
Origin: https://android.googlesource.com/kernel/common/+/refs/heads/android-mainline/drivers/md/dm-bow.c
Signed-off-by: Mateusz Moscicki <m.moscicki2@samsung.com>