Revert "[mlir][linalg] Introduce transpose semantic to 'linalg.matmul' ops. (#104783)"

This reverts commit 8d08ebb and
99c8557, which is a fix-up on top of the former.

I'm reverting because this commit broke two tests:
  mlir/test/python/integration/dialects/linalg/opsrun.py
  mlir/test/python/integration/dialects/transform.py
See https://lab.llvm.org/buildbot/#/builders/138/builds/4872

I'm not familiar with the tests, so I'm leaving it to the original author
to either remove or adapt the broken tests, as discussed here:
  llvm/llvm-project#104783 (comment)

Author: cota

mlir/python/mlir/dialects/linalg/opdsl/ops/core_named_ops.py

@@ -383,6 +383,23 @@ def select(
     O[None] = TernaryFn.select(cond[None], lhs[None], rhs[None])
 
 
+@linalg_structured_op
+def matmul(
+    A=TensorDef(T1, S.M, S.K),
+    B=TensorDef(T2, S.K, S.N),
+    C=TensorDef(U, S.M, S.N, output=True),
+    cast=TypeFnAttrDef(default=TypeFn.cast_signed),
+):
+    """Performs a matrix multiplication of two 2D inputs.
+
+    Numeric casting is performed on the operands to the inner multiply, promoting
+    them to the same data type as the accumulator/output.
+    """
+    domain(D.m, D.n, D.k)
+    implements(ContractionOpInterface)
+    C[D.m, D.n] += cast(U, A[D.m, D.k]) * cast(U, B[D.k, D.n])
+
+
 @linalg_structured_op
 def quantized_matmul(
     A=TensorDef(T1, S.M, S.K),