roll: third_party/pigweed pw_chrono_zephyr: Implement Cancel

Implement Cancel API to match destructor.

Manual Testing:
Using a Zephyr platform
1. Cancel timer after expiration -> Observe timer callback invoked.
2. Cancel timer before expiration -> Observe no timer callback.

Original-Bug: b/479294305
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/375712
Original-Revision: b8ee6360588864a9417d800c0ac6eba7beabe44f

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 8fbbc0b99de700..b8ee6360588864
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8689064728315903457
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia69c8982af150d0f7e9f8e78a5216d0e600cfc94
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/378512

third_party/pigweed

diff --git a/third_party/pigweed b/third_party/pigweed
index 8fbbc0b..b8ee636 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 8fbbc0b99de700cb0e2d67b2f1a3819ccc01ccaa
+Subproject commit b8ee6360588864a9417d800c0ac6eba7beabe44f