roll: pigweed, pw_toolchain: pw_sys_io: Remove multiplexer, constraints

Original-Bug: 347998044
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/218736
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>

https://pigweed.googlesource.com/pigweed/pigweed
pigweed, pw_toolchain Rolled-Commits: f588ba91c9de167..8b8ad3820dff2e6
Roller-URL: https://ci.chromium.org/b/8743843296180308161
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I9076f782bc30a402653dc4519488d26f1e485c72
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/quickstart/bazel/+/218784
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index da2d5eb..dcdcf75 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -84,8 +84,8 @@
     name = "pigweed",
     # ROLL: Warning: this entry is automatically updated.
     # ROLL: Last updated 2024-06-28.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8743844105167495281.
-    commit = "f588ba91c9de1678ba8716df34ba38d239f6e92c",
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8743843296180308161.
+    commit = "8b8ad3820dff2e6c5b7670bcd8355178b2d1b163",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed.git",
 )
 
@@ -93,8 +93,8 @@
     name = "pw_toolchain",
     # ROLL: Warning: this entry is automatically updated.
     # ROLL: Last updated 2024-06-28.
-    # ROLL: By https://cr-buildbucket.appspot.com/build/8743844105167495281.
-    commit = "f588ba91c9de1678ba8716df34ba38d239f6e92c",
+    # ROLL: By https://cr-buildbucket.appspot.com/build/8743843296180308161.
+    commit = "8b8ad3820dff2e6c5b7670bcd8355178b2d1b163",
     remote = "https://pigweed.googlesource.com/pigweed/pigweed.git",
     strip_prefix = "pw_toolchain_bazel",
 )