LU-9121 lnet: ioctl handler for "delete policy"

LU-9121 lnet: ioctl handler for "delete policy"

The ioctl handler for "delete policy" deletes
a policy with the given index value. It
returns 0 if a policy with that index is found
else it returns -EINVAL.

Change-Id: I037c6808e71e5c13ccf46c243145b0ce6f1229cb
Test-Parameters: trivial testlist=lnet-selftest,sanity-lnet
Signed-off-by: Sonia Sharma <sharmaso@whamcloud.com>
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34552
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>