Remove vestigial SK_LEGACY_NEAREST_SAMPLE_MATRIX_TWEAK guard

Bug: skia:13752
Change-Id: Ib16f068d6620f53090f36f4ecd5de83939785b7b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/615396
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Florin Malita <fmalita@google.com>
Commit-Queue: Florin Malita <fmalita@google.com>
Auto-Submit: Brian Salomon <bsalomon@google.com>
1 file changed