fw/comm/ble/kernel_le_client: fix unused variable warning in release

The `removed` variable is only read inside `#if !RELEASE`, causing an
unused-but-set-variable error in release builds. Mark it as unused to
suppress the warning.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>

Author: gmarull

src/fw/comm/ble/kernel_le_client/kernel_le_client.c

@@ -170,7 +170,7 @@ static const KernelLEClient s_clients[KernelLEClientNum] = {
 static void prv_handle_services_removed(PebbleBLEGATTClientServicesRemoved *services_removed) {
   PebbleBLEGATTClientServiceHandles *service_remove_info = &services_removed->handles[0];
   for (int s = 0; s < services_removed->num_services_removed; s++) {
-    bool removed = false;
+    bool removed __attribute__((unused)) = false;
     for (int c = 0; c < KernelLEClientNum; c++) {
       const KernelLEClient * const client = &s_clients[c];
       if (uuid_equal(&service_remove_info->uuid, client->service_uuid)) {