LU-5396: define __user for userspace

LU-5396: define __user for userspace

Structures used by ioctl are shared with the kernel. Some of these
structures will have the __user annotation for sparse, and thus __user
needs to be defined in user space

Change-Id: I2a4087a2faea0849cc816515c4aa9871699acf55
Signed-off-by: frank zago <fzago@cray.com>
Reviewed-on: http://review.whamcloud.com/11480
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>