LU-5396: use gfp_t for gfp mask, instead of (unsigned) int

LU-5396: use gfp_t for gfp mask, instead of (unsigned) int

This fixes sparse warnings, such as:

  .../echo.c:670:62: warning: incorrect type in initializer
                              (different base types)
  .../echo.c:670:62:    expected int [signed] gfp_mask
  .../echo.c:670:62:    got restricted gfp_t

gfp_t was introduced in 2.6.14 (end of 2005), so that should
work all recent distributions.

Besides using gfp_t, there is no code change.

Signed-off-by: frank zago <fzago@cray.com>
Change-Id: I3464fb21c47c174c3a04cb512ce05e0e9de146fb
Reviewed-on: http://review.whamcloud.com/11200
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Jenkins
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>