msm: camera: isp: Correct the active req cnt assignment order

We need to reset the active req cnt before assigning
new value. Also move the log behind the active req cnt
assignment.

CRs-Fixed: 2517421
Change-Id: I38f418f79f5f1adcb8b29bc870f904cd1f925bfc
Signed-off-by: Depeng Shao <depengs@codeaurora.org>