staging: lustre: libcfs: merge code from libcfs_ioctl into libcfs_ioctl_getdata

This is apart of the cleanup of libcfs_ioctl* code. In this
part some of the code in libcfs_ioctl is migrated into
libcfs_ioctl_getdata_len() which is renamed libcfs_ioctl_getdata()

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5435
Reviewed-on: http://review.whamcloud.com/11313


Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>