ptserver: Check for -restricted in SPR_Delete

ptserver: Check for -restricted in SPR_Delete

Currently, all prdb write operations, except for SPR_Delete, will fail
with PRPERM if called by a non-system:administrators caller while
restricted mode is active.  SPR_Delete is missing this check, and so
is not affected by the -restricted option.

Fix this by inserting the same check for -restricted as all other code
paths that check for -restricted.

Reviewed-on: https://gerrit.openafs.org/13374
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 2e556c0f23ae439c804352cf51fcf30878b03c7a)

Change-Id: I9a31cf4e6490aa13dc0c239d2660fc146553ee75
Reviewed-on: https://gerrit.openafs.org/13688
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>