dm: set QUEUE_FLAG_DAX accordingly in dm_table_set_restrictions()

commit ad3793fc3945173f64d82d05d3ecde41f6c0435c upstream.

Rather than having DAX support be unique by setting it based on table
type in dm_setup_md_queue().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>