The utility function parse_integrity_options is used to both validate
integritytab options or validate and return values. In the case where
we are validating only and we have specific value options we will
assert.
This adds support for dm integrity targets and an associated
/etc/integritytab file which is required as the dm integrity device
super block doesn't include all of the required metadata to bring up
the device correctly. See integritytab man page for details.
Tony Asleson