[roll third_party/pigweed] pw_{rpc, transfer}: Remove unused imports

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/95365

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: d20c1242ea54ac7..6c0716d7fb60f18
Roller-URL: https://ci.chromium.org/b/8813691802624917761
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8813691802624917761
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I08cf5428bd981058518ee06c479516826ec4a3fc
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/95408
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index d20c124..6c0716d 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit d20c1242ea54ac76bbf2104d98b88b52d2919f1e
+Subproject commit 6c0716d7fb60f1854fef10edb352b79eb9deaa75