redhat: Correct permissions on systemd unit files

redhat: Correct permissions on systemd unit files

Change the systemd unit file permissions created via
openafs.spec to be 0644 instead of 0755.  Having the
systemd unit files be executable will trigger a systemd
warning.

FIXES 132662

Reviewed-on: http://gerrit.openafs.org/12174
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit a4c4b786059ac7d5f9ecc5ec07727f000b62c13f)

Change-Id: I0ad33a93c963b7a2d242b43b7d94e2e3f5041e8d
Reviewed-on: http://gerrit.openafs.org/12196
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>