90crypt: Fixed crypttab_contains() to also work with device path in /etc/crypttab

blkid is not available when this function is called, so block_uuid.map is put into
the initrd, mapping block devices from /etc/crypttab to UUIDs.

This fixes a bug where udev rules were created by mistake as crypttab_contains()
returned false for devices specified by path in /etc/crypttab which resulted in
error messages during boot.

Signed-off-by: Julian Wolf <juwolf@suse.de>
Merge branch 'sles12' of https://github.com/juwolf/dracut into sles12