roll: third_party/pigweed: pw_cpu_exception_cortex_m: Fix assembly

Use unified assembly ARM instruction syntax.

Original-Bug: b/261603269
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/223131
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 386caa7e2f4b97e..f73539ca94138de
Roller-URL: https://ci.chromium.org/b/8742214406610470017
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia218d8156b052c738b0beed4adf5ac12b7cf755d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/223561
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 386caa7..f73539c 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 386caa7e2f4b97ee3afe2aacd52616d00c2801b2
+Subproject commit f73539ca94138de3b605c08cea9e9e9ff3e35b7e