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>

fs/nfs/file.c

@@ -64,7 +64,11 @@ const struct file_operations nfs_file_operations = {
 	.write		= do_sync_write,
 	.aio_read	= nfs_file_read,
 	.aio_write	= nfs_file_write,
+#ifdef CONFIG_MMU
 	.mmap		= nfs_file_mmap,
+#else
+	.mmap		= generic_file_mmap,
+#endif
 	.open		= nfs_file_open,
 	.flush		= nfs_file_flush,
 	.release	= nfs_file_release,