LU-9121 lnet: Delete a selection policy

LU-9121 lnet: Delete a selection policy

This patch adds the function lustre_lnet_del_udsp()
which takes index of the udsp as input and calls
the IOC_LIBCFS_DEL_UDSP ioctl handler to
delete the udsp with that index value.

Change-Id: Ib81c79fd4e76f4e8fbd84709e08cb5d29a059e63
Test-Parameters: trivial testlist=lnet-selftest,sanity-lnet
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Signed-off-by: Sonia Sharma <sharmaso@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34553
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>