NFS: Fix uninitialized rpc_wait_queue

NFS: Fix uninitialized rpc_wait_queue

BugLink: http://bugs.launchpad.net/bugs/1724669
commit 68ebf8fe3bce8c167cf83fbd681c1eb1ed419c6c upstream.

Michael Sterrett reports a NULL pointer dereference on NFSv3 mounts when
CONFIG_NFS_V4 is not set because the NFS UOC rpc_wait_queue has not been
initialized.  Move the initialization of the queue out of the CONFIG_NFS_V4
conditional setion.

Fixes: 7d6ddf88c4db ("NFS: Add an iocounter wait function for async RPC tasks")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>