LU-6202 misc: delete OBD_IOC_PING_TARGET ioctl

LU-6202 misc: delete OBD_IOC_PING_TARGET ioctl

The OBD_IOC_PING_TARGET ioctl was removed from tool usage in
Lustre v2_5_60_0-27-g122aadd and replaced with a /proc interface.
It is no longer needed and can be removed.

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I7e4881edc50526e28b1a1aa039a4c986593ebbe5
Reviewed-on: https://review.whamcloud.com/33691
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>