LU-5349 include: use __vmalloc() to avoid __GFP_FS default

When possible, try to Direct use of __vmalloc() which allows
for protection flag specification, and particularly to not
set __GFP_FS, which can cause some deadlock situations in our
code.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: I25fc4a55374c09c12156b2a2f8d8b2434b4cd689
Reviewed-on: http://review.whamcloud.com/11190
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>