Remove clamping of kPlus with F16 configs

The most common use-case for F16 is to draw things that are explicitly
outside of [0,1]. We can't prevent out-of-range values in general, users
could just draw out-of-range content in src mode. We've decided that
it's best to avoid surprising behavior, and trust the user in these
situations.

This effectively reverts https://skia-review.googlesource.com/c/skia/+/48183

Bug: skia:
Change-Id: I71c2dd925c567e2862d96ab70c752f19245a69c4
Reviewed-on: https://skia-review.googlesource.com/140500
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/tests/DrawOpAtlasTest.cpp b/tests/DrawOpAtlasTest.cpp
index e065bf0..97524cd 100644
--- a/tests/DrawOpAtlasTest.cpp
+++ b/tests/DrawOpAtlasTest.cpp
@@ -202,7 +202,7 @@
                                                                      rtc.get(), paint,
                                                                      SkMatrix::I(), text,
                                                                      16, 16);
-    op->finalize(*context->contextPriv().caps(), nullptr, GrPixelConfigIsClamped::kNo);
+    op->finalize(*context->contextPriv().caps(), nullptr);
 
     TestingUploadTarget uploadTarget;