pw_bluetooth_sapphire: clang-tidy fix

Fixes another instance of Fixes an instance of
https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-equals-delete.html.

Bug: 392135941
Change-Id: Idbcb64dfda781862c7cf2e6c708295257bf1980b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/266893
Pigweed-Auto-Submit: Ted Pudlik <tpudlik@google.com>
Docs-Not-Needed: Ted Pudlik <tpudlik@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>

pw_bluetooth_sapphire/host/common/public/pw_bluetooth_sapphire/internal/host/common/error.h

@@ -53,6 +53,7 @@ struct ProtocolErrorTraits {
 
 // Marker used to indicate that an Error holds only HostError.
 class NoProtocolError {
+ public:
   constexpr NoProtocolError() = delete;
 };