fractional_maxpool3d: port to structured kernel (#70414)
Summary:
Port fractional maxpool 3d to structured kernel
Fixes https://github.com/pytorch/pytorch/issues/55070
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70414
Reviewed By: zdevito, wenleix
Differential Revision: D33572110
Pulled By: bdhirsh
fbshipit-source-id: 1f89eb511335f51cc7abbb0230e165da8752f9fc
