LU-6746 ptlrpc: Move IT_* definitions to lustre_idl.h

LU-6746 ptlrpc: Move IT_* definitions to lustre_idl.h

Put IT_* definitions into an enum, as they're sent over the wire,
adjust calls, print statements, etc. to use the new enum.

Signed-off-by: Ben Evans <bevans@cray.com>
Change-Id: Ie6ad700ac185459ace72ea67563864e43c548ec3
Reviewed-on: http://review.whamcloud.com/16228
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>