The channel members lcids, rcids synchronised using the idr_lock is
accessed in both atomic/non-atomic contexts. The readers are not
currently synchronised.  That no correct, so add the readers as well
under the lock and use a spinlock.
Acked-by: NArun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: NSricharan R <sricharan@codeaurora.org>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>