audio: Fix the type used for timekeeping

On 32-bit builds, the 'long' type is 32 bit. Thus, it can not
be used to store the value returned from 'uptimeNanos'.

Bug: 318055805
Test: atest CtsMediaAudioTestCases
Change-Id: I4abf72415b7241728d3ddb1d11043dfd59a8d08a
3 files changed