sthal: check audio extn init result in stdev init

STHAL init may be successful even though audio extn
init fails in pal/agm side, this may cause crash
when ST framework try to get st properties.

Check audio extn init result to avoid stdev created
with pal/agm initialization failure.

Change-Id: Iac1deca81339b447a0947430ada762c8e5306425
2 files changed