net: qrtr: Stop rx_worker before freeing node

As the endpoint is unregistered there might still be work pending to
handle incoming messages, which will result in a use after free
scenario. The plan is to remove the rx_worker, but until then (and for
stable@) ensure that the work is stopped before the node is freed.

Change-Id: Ic35d1c0f5e5e4f297c7c05dd09c7c8a4d8b23cf4
Fixes: bdabad3e ("net: Add Qualcomm IPC router")
Cc: stable@vger.kernel.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Git-commit: 73f0c11d
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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