LU-6450 mdd: Remove unused MAY_ constants

LU-6450 mdd: Remove unused MAY_ constants

Remove unused MAY_ constants from lustre_idl.h
Remove dead code from mdd_permission()

Signed-off-by: Ben Evans <bevans@cray.com>
Change-Id: I722f55eac88c7143555e680f72971b96791b00ae
Reviewed-on: http://review.whamcloud.com/15398
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>