hrtimer: make sure PINNED flag is cleared after removing hrtimer

Change-Id: I1a3211bc0d5d310c7fa7b92dc44ec6c4722dd7b9
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[forward port to 3.18]
Signed-off-by: Santosh Shukla <santosh.shukla@linaro.org>
Git-commit: d6c894e515b4cd93c3a08e7c60cce0aa5118c656
Git-repo: git://git.linaro.org/people/mike.holmes/santosh.shukla/lng-isol.git


Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>