ccodec: FetchLinearBlock() pass usage argument to C2BlockPool

Originally the usage argument is dropped when calling
CalculateMinMaxUsage(). This CL changes to union the usage argument
and the minimum usage, then pass it to the C2BlockPool.

Bug: 170694288
Test: android.media.cts.MediaCodecTest#testException
Change-Id: I057d6bd1c25112126492361d39192d8d6f4074e5
(cherry picked from commit 4ebf813ab08cbbb2b5edea62649cee925bb6499d)