[dev][platform-bus] Fix returning error from proxied protocols

TEST: manual testing on VIM2

ZX-2602 #done

Change-Id: Icf27ba87fce12e14672ac50235b5a778eedb77f0
diff --git a/system/dev/bus/platform/platform-device.cpp b/system/dev/bus/platform/platform-device.cpp
index 678f2e4..f735488 100644
--- a/system/dev/bus/platform/platform-device.cpp
+++ b/system/dev/bus/platform/platform-device.cpp
@@ -541,6 +541,9 @@
             .resp_actual_handles = 0,
         };
         status = bus_->Proxy(&args);
+        if (status == ZX_OK) {
+            status = args.resp->status;
+        }
         resp_len = args.resp_actual_size;
         resp_handle_count = args.resp_actual_handles;
         break;