libvpx

Remvoe EIGHTTAP_SHARP filter check for non-rd mode.

Using EIGHTTAP and EIGHTTAP_SMOOTH seem sufficient.
Hard to see any visual gain from allowing EIGHTTAP_SHARP, and it is
rarely selected.

PSNR/SSIM metrics go up by ~0.18/0.14%.

Change-Id: I96fa0d98f9321b913e3ebcd464d4ff3c63018791