msm: camera_v2: fix close sequence of isp stats stream

Stats stream close is failing in dual vfe usecases, due to
wrong array index is used while deleting the stream.

Change-Id: I8fa4b73f257439b13bddadd1b4edd6d2a5508c69
Signed-off-by: Srikanth Uyyala <suyyala@codeaurora.org>