Revert "net: qrtr: Stop rx_worker before freeing node"

This reverts commit abb04d0a.

This is a preparation change for merging android-4.19-q.77 into
msm-4.19 branch. Equivalent logic is already committed via:

8fd658e5 net: qrtr: Add snapshot of QRTR drivers

Change-Id: Ie741d4745f662a5bbb9baa57714856e90a15b8be
Signed-off-by: Ivaylo Georgiev <irgeorgiev@codeaurora.org>