Support turning on DM-Verity's in-line verification

Add libdm support for turning on DM-Verity's in-line verification
of small (<8k) blocks by setting the try_verify_in_tasklet option.

Note that this change does not actually turn on the optimization,
which will be done in a follow-up change.

Bug: 394514982
Test: Manual, using  ./fio --name=rand_read --ioengine=psync --rw=randread --bs=4K --direct=1 --numjobs=8 --runtime=60 --time_based --group_reporting --filename=/dev/block/dm-17
Change-Id: Iad953a98e7d7cc17b192f879391397a4982757a0