[MHLO] Init MHLO matmul op patterns

See RFC #999

Co-authored-by: Bairen Yi [email protected]
Co-authored-by: Jiawei Wu [email protected]
Co-authored-by: Tianyou Guo [email protected]
Co-authored-by: Xu Yan [email protected]
Co-authored-by: Ziheng Jiang [email protected]

Author: Tanyo Kwok

lib/Conversion/TorchToMhlo/CMakeLists.txt

@@ -3,6 +3,7 @@ add_mlir_conversion_library(TorchMLIRTorchToMhlo
   MhloLegalizeUtils.cpp
   BasicOp.cpp
   GatherOp.cpp
+  MatmulOp.cpp
   ViewLikeOps.cpp
 
   ADDITIONAL_HEADER_DIRS