fix some typos in bos_setrestricted

the real name of the command is: 'bos setrestricted'
it is sufficient to name 'bos install' only once

Change-Id: Ic68f7cb55466e1c92c34eeda37c0a64a11b7e4d8
Reviewed-on: http://gerrit.openafs.org/8990
Reviewed-by: Ken Dreyer <ktdreyer@ktdreyer.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>