fix BUILD_MOBILE_BENCHMARK typo (#48515)
Summary:
BUILD_MOBILE_BENCHMARKS in CMakeLists.txt should be BUILD_MOBILE_BENCHMARK.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48515
Reviewed By: albanD
Differential Revision: D25198724
Pulled By: mrshenli
fbshipit-source-id: 12765d10c272da04cb104202fcbabc6a0b007c5e