CRAS: iodev_list - Fix pinned stream check

Need to check is_pinned flag of a rstream otherwise its member
'pinned_dev_idx' could collide with the index of fallback iodev.

BUG=chromium:666405
TEST=None

Change-Id: I973d2eb78e69f08b73e7ba819c5d7ada12969ade
Reviewed-on: https://chromium-review.googlesource.com/413789
Commit-Ready: Hsinyu Chao <hychao@chromium.org>
Tested-by: Hsinyu Chao <hychao@chromium.org>
Reviewed-by: Chinyue Chen <chinyue@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
1 file changed