[roll third_party/pigweed] pw_digital_io: Add Android.bp for proto/rpc

pw_digital_io RPC services proto and header files are needed for a
downstream project.

Test: Copy into external/pigweed in Android tree and consume in binary
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/176270

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 6e3b329a579ccdd..2f1d686f9f82655
Roller-URL: https://ci.chromium.org/b/8766927572272294273
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6bcd0fdc05100fdb49012d16e22710e6914706a5
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/176599
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 6e3b329..2f1d686 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 6e3b329a579ccddf532205c6671169c304dc6224
+Subproject commit 2f1d686f9f82655444bda5a9721db2ff661506c0