msm: camera: isp: Do not update lpm mode for inactive streams.

If stream is inactive then there is no need to update lpm mode
for the stream since the stream is non operational.

Change-Id: I5c719211dc2bfdc67365a3716bd79c7fa54a818f
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>