Allow more commands to pass persistent reservation according to SPC-4 r37.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271845 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Don't use nvl in case of a failure.

Reported by:	Coverity
CID:		1238922


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271847 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f