Increase number of iterations for benchmarking (#6209)

Summary:
Tweak on the iterations for the non-genai models

Pull Request resolved: https://github.com/pytorch/executorch/pull/6209

Reviewed By: huydhn, shoumikhin, kirklandsign

Differential Revision: D64367752

Pulled By: guangy10

fbshipit-source-id: 26084631c0c7a0cd71a93cb8e542e16f2cf7a336