IPoIB: Get rid of useless test of queue length

IPoIB: Get rid of useless test of queue length

In neigh_add_path(), the queue of delayed packets can never be full,
because the queue is always freshly created and cannot be found by any
other code path.  In fact, the test of the queue length is worse than
useless: if somehow the test ever triggered and path_rec_start() also
failed, then dev_kfree_skb_any() will be called twice on the same skb.
Fix this by deleting the useless test.  Pointed out by Michael
S. Tsirkin <mst@mellanox.co.il>.

Signed-off-by: Roland Dreier <rolandd@cisco.com>