C2SoftMp3Dec: fix floating point exception

outTimeStamp and mProcessedSamples are calculated from
samplingRate and numChannels respectively. If either
of them is 0, it will lead to divide by zero error.
This patch adds a check on both these parameters.

Test: clusterfuzz generated poc in bug
Test: atest android.mediav2.cts.CodecDecoderTest
Test: atest VtsHalMediaC2V1_0TargetAudioDecTest
Bug: 193363472

Change-Id: Ib268d63fa28b2b4d83165c2e3deccbb2bac2d92b