Regression: fix mounting NFS when NFSv3 support is not compiled

Trying to mount NFS (root partition in my case) fails if CONFIG_NFS_V3
is not selected. nfs_validate_mount_data() returns EPROTONOSUPPORT,
because of this check:

#ifndef CONFIG_NFS_V3
	if (args->version == 3)
		goto out_v3_not_compiled;
#endif /* !CONFIG_NFS_V3 */

and args->version was always initialized to 3.

It was working in 2.6.36

Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>