Revert "implemented GrMtlSampler for metal gpu backend"

This reverts commit 93fa10fbbc74cae8e57291acfe0c6c06f4ba8ff7.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> implemented GrMtlSampler for metal gpu backend
> 
> Bug: skia:
> Change-Id: I936e5510e5ee146c0fc6bdbc0d5f5352359fbe7d
> Reviewed-on: https://skia-review.googlesource.com/145893
> Commit-Queue: Timothy Liang <timliang@google.com>
> Reviewed-by: Greg Daniel <egdaniel@google.com>

TBR=egdaniel@google.com,timliang@google.com

Change-Id: I4184890610e3147abc63b7d9bdfa8ec8120a11ef
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/146580
Reviewed-by: Timothy Liang <timliang@google.com>
Commit-Queue: Timothy Liang <timliang@google.com>
3 files changed