Revert "binder: Prevent context manager from incrementing ref 0"

This reverts commit c5665caf.

This is a preparation change for merging android-5.4.58 into
msm-5.4 branch. The reverted change is causing UI unresponsive
issue.

Change-Id: I00a837a8706c3625ef736a4de8ce501df233f9a0
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>