LU-8733 gnilnd: Remove read capability of cksum_test procfile

LU-8733 gnilnd: Remove read capability of cksum_test procfile

When the old create proc interface was deprecated cksum_test was
updated  to use the new file operations table. Inadvertantly read
was left as a capability without actually defining a function
that the file would use when someone tried to read the file.
This causes a kernel crash when cksum_test is read, though it can
only be done by the root user.

The fix is to remove the .read op from the fops table for the
cksum_test proc entry

Test-Parameters: trivial
Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: I406b076f1b66b6d991694c69a9b748ed42c09f39
Reviewed-on: http://review.whamcloud.com/23255
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>