add tile test vectors

1920x1080

vp90-2-08-tile_1x2_frame_parallel.webm
vp90-2-08-tile_1x2.webm
vp90-2-08-tile_1x4_frame_parallel.webm
vp90-2-08-tile_1x4.webm

vpxenc blue_sky_1080p25.y4m \
  --codec=vp9 -p 2 \
  --frame-parallel=${fpm} \
  --tile-columns=${tc} \
  --limit=10 \
  --auto-alt-ref=1 \
  --lag-in-frames=5 \
  --target-bitrate=2500

Change-Id: Id9c94b722cc553a6865d443a94e8482c78b038bb