CEC VTS: Improve testGetVendorId test

Add validation to the response from testGetVendorId HAL API.

Bug: 157402557
Test: vts-tradefed run commandAndExit vts-hal-tv -m VtsHalTvCecV1_0Host
Change-Id: Id1382ba77d1e36e45e7bf4e3aeaf4aadfdb7c11e
1 file changed