benchmarks/patches: fix corrupt patch file error (#6124)

Fixes the following error:
$ git apply ../pytorch/xla/benchmarks/patches/mismatched_batch_size.patch error: corrupt patch at line 14

benchmarks/patches/mismatched_batch_size.patch

@@ -2,7 +2,7 @@ diff --git a/torchbenchmark/util/model.py b/torchbenchmark/util/model.py
 index 8593ba4c..57fef507 100644
 --- a/torchbenchmark/util/model.py
 +++ b/torchbenchmark/util/model.py
-@@ -182,6 +182,7 @@ class BenchmarkModel(metaclass=PostInitProcessor):
+@@ -182,6 +182,8 @@ class BenchmarkModel(metaclass=PostInitProcessor):
 
          # use the device suggestion on CUDA inference tests, key should be either eval_batch_size or train_batch_size
          device_batch_size_key = f"{self.test}_batch_size"