net: qrtr: Fix hello packet drop memory leak

If a node_enqueue is called on a node that has not finished the hello
packet negotiation, the packet to be enqueued will be dropped. Make
sure to free this dropped packet.

Change-Id: I52a6f5d6b07fff272e3912d85221e7f6540cfa33
Signed-off-by: Chris Lew <clew@codeaurora.org>