Clamp in GrBicubicEffect (to match SW and for general sanity)

Bug: skia:8809
Change-Id: I9f5b6428113602929b3a1b45c25b623e8da0e264
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/200512
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
5 files changed