Use unique_fd::ok() instead of -1 comparison

Test: mma
Bug: 302723053
Change-Id: I744bdfe735624ad9f95a7d448919e7bd2e430098
diff --git a/libs/binder/FdTrigger.cpp b/libs/binder/FdTrigger.cpp
index a1fbbf3..895690f 100644
--- a/libs/binder/FdTrigger.cpp
+++ b/libs/binder/FdTrigger.cpp
@@ -53,7 +53,7 @@
 #ifdef BINDER_RPC_SINGLE_THREADED
     return mTriggered;
 #else
-    return mWrite == -1;
+    return !mWrite.ok();
 #endif
 }