C2SoftOpusEnc: Fix integer overflows leading to crash by changing data type

Bug: 211910627

Test: POC in bug descriptions
Test: atest VtsHalMediaC2V1_0TargetAudioEncTest
Test: atest CtsMediaTestCases:EncoderTest

Change-Id: I72fee83ae27d3f446b1584fd4fd047e93a0a01d9
2 files changed