add 15 tap filter in the parallel_deblocking experiment

this change added back the original 15 tap filter from VP9 back into
the parallel_deblocking experiment. when transform size of both blocks
along the edge is greater than 16x16, 15 tap filter is used.

Change-Id: Ieae0393b66b1168572292bcebabd2707058b7f1d
2 files changed