Account for removed libxsmm_gemm_diff.c.
Account for removed libxsmm_gemm_diff.c.

hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm,hfp/tensorflow-xsmm