Return immediately when prop is not found

- when VHAL prop is not supported, getPropConfigs calls hidl callback
with INVALID_ARG and has to return.
- otherwise, there will be two callbacks invoked from VHAL.

Bug: 168834308
Test: seahawk should boot up
Change-Id: I41f5ddf26b9ba70221d59bae10d7ca9a2133a9eb
Merged-In: I41f5ddf26b9ba70221d59bae10d7ca9a2133a9eb
(cherry picked from commit 26abceef)