IOMX: consolidate createInputSurface APIs

- Create GraphicBufferSource in IOMX regardless of persistency.

- Remove createInputSurface on IOMXNode, only keep setInputSurface
  which accepts either a persistent or non-persistent surface.

- Instead of holding a IGraphicBufferConsumer, hold
  IGraphicBufferSource across session as the persistent surface.

- Fix up GraphicBufferSource to allow usage across sessions.
  GraphicBufferSource itself becomes agnostic to persistency.

- Remove max encoder input buffers profiling code.

bug: 31399200
Change-Id: I15ed52cc64509fd87736372a580abf7b51bf4de7