Remove sampler support from .fp files

Change-Id: I46e5bc6d39aa185b26436e1795f50a0c7bb9905b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/411307
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
8 files changed