roll: third_party/pigweed targets/rp2040: Add default linker script targets

Add rp2040_linker_script and rp2350_linker_script targets which
depend on the pico-sdk default linker script for now.

Next step is to update downstream projects to reference these
targets.

Finally, http://pwrev.dev/234155 will modify these targets to use
the custom linker script.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/242172
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Original-Revision: a222b3f929369cba8116470a74384ec9afe97f44

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: f60e87048d4009..a222b3f929369c
Roll-Count: 1
Roller-URL: https://ci.chromium.org/b/8733994431045044529
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I24e30ce5e813736ec72c2961c1f63ba0905f1b65
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/242313
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.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 f60e870..a222b3f 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit f60e87048d40096d7b005f4d40e42872b9bae76e
+Subproject commit a222b3f929369cba8116470a74384ec9afe97f44