OpenZFS 7162 - Intermittent failures from ro_props_001_pos

OpenZFS 7162 - Intermittent failures from ro_props_001_pos

Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/7162
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/9ec0cbeb
Closes #5511
Closes #5779