only run embeddingbag benchmark on cpu (#30106)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30106
as title
Test Plan:
```
buck run mode/opt //caffe2/benchmarks/operator_benchmark:benchmark_all_other_test -- --tag_filter all --iterations 1 --device cuda --operators embeddingbag
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# PyTorch/Caffe2 Operator Micro-benchmarks
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# Tag : all
Reviewed By: hl475
Differential Revision: D18598198
fbshipit-source-id: 9b7d103410f1183fdf6776047ea2ef8dba4b7831
