msm: vidc: Fix dead lock during long stability run

During long run stability there is a possibility
that first thread (T1) which has acquired sync lock
during streamon, is waiting for ctrl lock to be
released by second thread (T2) and second thread (T2)
while performing a set ctrl, has already acquired ctrl lock
and is waiting for sync lock to be released by T1 there
by creating a deadlock condition.

With this change, ctrl lock is avoided by keeping the
operating rate as part of instance variable and not by
getting it from the control directly.

Change-Id: Ie5e3dbcb9007fb2961c8a01f292fcce193f33c15
Signed-off-by: Paras Nagda <pnagda@codeaurora.org>