fix bug - executing FDPIC ELF on NFS mount triggers BUG() at mm/nommu.c:862:/do_mmap_private()

NFS needs a NOMMU version mmap function to support uClinux on NOMMU machine
http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_id=141&tracker_item_id=3992

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Cc: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>