staging: lustre: lmv: remove unused placement parameter

Remove the unused lmv.*.placement parameter along with supporting
functions and struct members.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-7674
Reviewed-on: http://review.whamcloud.com/18019


Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: Frank Zago <fzago@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>