hal: Fix for a native crash in select_devices

In case of speaker protection, stream.in is not filled
and hence when it tries to access stream.in->devices for
spkr-vi-record usecase,crash occurs.In case of HDMI
keep_alive usecase,stream.out is not filled.
Add a null check before accessing stream.in and
stream.out pointers.

Change-Id: I5fafaa71d13ce234908dc2e24979d69a38435f62
CRs-Fixed: 1076923