LU-6401 uapi: turn lustre_ioctl.h into a proper UAPI header

LU-6401 uapi: turn lustre_ioctl.h into a proper UAPI header

Remove all the complex inline functions. Move all the user land
specific functions into the userland library. Unwind the kernel
specific functions and move obd_ioctl_is_valid() into the kernel
source file linux-module.c.

Change-Id: I91e69a21231f3effd23b191b6df9b5515a2ccc64
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/24568
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>