roll: third_party/pigweed pw_bluetooth_sapphire: Handle inbound L2CAP Flow Control Credit Ind

Handle the L2CAP Flow Control Credit Ind signaling packet by adding
credits to CreditBasedFlowControlTxEngine.

Fix bug in CreditBasedFlowControlTxEngine that added an extra Basic
L2CAP header. Fragmenter already adds a Basic L2CAP header.

Original-Bug: 42178956
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/279912
Original-Revision: 231ff06afdc3704823efa9c8e34115c961f6de42

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 6b17f4eaa79d42..231ff06afdc370
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8718670335912177489
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ifcc0d2d8aeb4405769410080b2e809f2f2880936
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/280953
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 6b17f4e..231ff06 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 6b17f4eaa79d427095bf1c2d7f34365e47099472
+Subproject commit 231ff06afdc3704823efa9c8e34115c961f6de42