pw_sync_threadx: Adjust ISL enum to make it bss eligible

Adjusts an enum's values to ensure that a value of 0 is used in the
constexpr constructor to ensure that the object is bss eligible
instead of requiring placement in data.

Change-Id: Ied32426852661b5b534b6e4682a0e52fa28a57ae
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/55027
Reviewed-by: Wyatt Hepler <hepler@google.com>
Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_sync_threadx/public/pw_sync_threadx/interrupt_spin_lock_native.h b/pw_sync_threadx/public/pw_sync_threadx/interrupt_spin_lock_native.h
index 567807f..6b6d3f7 100644
--- a/pw_sync_threadx/public/pw_sync_threadx/interrupt_spin_lock_native.h
+++ b/pw_sync_threadx/public/pw_sync_threadx/interrupt_spin_lock_native.h
@@ -19,9 +19,9 @@
 
 struct NativeInterruptSpinLock {
   enum class State {
-    kUnlocked = 1,
-    kLockedFromInterrupt = 2,
-    kLockedFromThread = 3,
+    kUnlocked = 0,
+    kLockedFromInterrupt = 1,
+    kLockedFromThread = 2,
   };
   State state;  // Used to detect recursion and interrupt context escapes.
   UINT saved_interrupt_mask;