change the epilogue of SLS to match the simd section (#21439)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21439
this bug got exposed after testing accuracy on shapes not multiples of 8
Reviewed By: jspark1105
Differential Revision: D15684759
fbshipit-source-id: 2950f2bd87ee1d8e539148285a14c755f606b3a7
