[roll third_party/pigweed] pw_digital_io: rename from pw_gpio

As per discussion in the change that adds pw_gpio, we would like to name
the module pw_digital_io. Doing the rename in a follow-up change makes
the original discussion easier to follow.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98040

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 7287d35a556ebdb..86312ba21e9d173
Roller-URL: https://ci.chromium.org/b/8811161143733957025
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811161143733957025
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I5624be027dc1b098855b82e32d283926f5e5079c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/98542
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 7287d35..86312ba 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 7287d35a556ebdbb9f7380853dea8013aa4eaebd
+Subproject commit 86312ba21e9d173296a5c20ad474362291f9c080