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

This reverts commit 088f93d0.

This is a preparation change for merging android-4.14-q.147 into
msm-4.14 branch. Equivalent logic is already committed via:

31df2523 net: qrtr: Move rx worker to separate worker thread
05cc4548 net: qrtr: Flush work during release

Change-Id: Icdc4dbbe647c92251d67dbe140391bd1317235d1
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>