crypto: msm: fix issues in ce clock disable processing

In the situation of more than one requests, the ce clock may get
errorneously disabled even when there are active requests. The
scaling operation is then modified to fix the problem and ensure
all requests are completed when disable the clock. We also clean
up the related codes.

Change-Id: Icc4675fa7b3818f6f8befb513b56d9ae051b98de
Signed-off-by: Zhen Kong <zkong@codeaurora.org>