message: Update input/output types to match tflite restrictions for Mul,Neg,Pow.
  Also, disable invalid tests for conversion.
diff: @@ -1857,11 +1857,11 @@ def TFL_MulOp : TFL_Op<"mul", [ResultsBroadcastableShape, NoSideEffect, Commutat
  }];
  let arguments = (
  - ins AnyTensor:$lhs,
  - AnyTensor:$rhs,
  + ins TFL_TensorOf<[F32, I32, QI8, QUI8, QI16]>:$lhs,
  + TFL_TensorOf<[F32, I32, QI8, QUI8, QI16]>:$rhs,
  TFL_AFAttr:$fused_activation_function);
  - let results = (outs AnyTensor:$output);
  + let results = (outs TFL_TensorOf<[F32, I32, QI8, QUI8, QI16]>:$output);
  let hasFolder = 1;
  @@ -1881,9 +1881,9 @@ def TFL_NegOp: TFL_Op<"neg", [NoSideEffect, SameOperandsAndResultType]> {
  Computes element-wise negation of input
  }];
  - let arguments = (ins AnyTensor:$x);
  + let arguments = (ins TFL_TensorOf<[F32, I32, I64]>:$x);
  - let results = (outs AnyTensor:$y);
  + let results = (outs TFL_TensorOf<[F32, I32, I64]>:$y);
  let hasOptions = 0b1;
  @@ -2033,10 +2033,10 @@ def TFL_PowOp : TFL_Op<"pow", [ResultsBroadcastableShape, NoSideEffect, NoQuanti
  }];
  let arguments = (
  - ins AnyTensor:$lhs,
  - AnyTensor:$rhs);
  + ins TFL_TensorOf<[F32, I32]>:$lhs,
  + TFL_TensorOf<[F32, I32]>:$rhs);
  - let results = (outs AnyTensor:$output);
  + let results = (outs TFL_TensorOf<[F32, I32]>:$output);
  let parser = [{ return mlir::impl::parseOneResultSameOperandTypeOp(parser, result); }];
  