Fix a null pointer access in Tuner VTS

With Vts suite "11_r4/7337463”, meet a crash issue when run case "PerInstance/TunerRecordHidlTest#LnbRecordDataFlowWithTsRecordFilterTest/0_default".
The crash is introduced by https://android.googlesource.com/platform/hardware/interfaces/+/7402e02ebc5d1a4d7f29e7900f0a069faa2236bc

The "mLnbId" is a null pointer but it does "*mLnbId = ids[0];" which will obviously lead to crash.
After changing to "mLnbId = &ids[0];", all cases can PASS.

Bug: 189974145
Change-Id: Ic593bfd00fa53365af4bbfeb7512e392f516468c