C2SoftDec: Align stride to 128 for avc, hevc and mpeg2 decoders

Some platforms allocate graphic buffers with a stride that is
aligned to 64. avc, hevc and mpeg2 decoders require chroma stride
to be half of luma stride. These two requirements would mean,
when allocating buffers, plugins need to align width to 128.

Bug: 197307855
Bug: 198747048
Test: atest CtsMediaV2TestCases

Change-Id: Idd5bd912fb88ad609e87e08870443a0c814c91d7