Fix NCW Global Average Pooling on WAsm SIMD

PiperOrigin-RevId: 324898342
diff --git a/src/xnnpack/params-init.h b/src/xnnpack/params-init.h
index 5a92191..255503a 100644
--- a/src/xnnpack/params-init.h
+++ b/src/xnnpack/params-init.h
@@ -491,9 +491,9 @@
 
     const uint32_t w = (width - 1) & 3;
     params->scalar.mask[0] = UINT32_C(0xFFFFFFFF);
-    params->scalar.mask[1] = (int32_t) (w >= 1);
-    params->scalar.mask[2] = (int32_t) (w >= 2);
-    params->scalar.mask[3] = (int32_t) (w >= 3);
+    params->scalar.mask[1] = -(int32_t) (w >= 1);
+    params->scalar.mask[2] = -(int32_t) (w >= 2);
+    params->scalar.mask[3] = -(int32_t) (w >= 3);
   #endif
 }