[mlir] remove RegionBranchOpInterface from linalg ops

[ftynse]

Summary

Linalg structure ops do not implement control flow in the way expected
by RegionBranchOpInterface, and the interface implementation isn't
actually used anywhere. The presence of this interface without correct
implementation is confusing for, e.g., dataflow analyses.

[ftynse]

Bazel breakage is irrelevant.

mlir/include/mlir/Dialect/Linalg/IR/LinalgStructuredOps.td

 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LINALG_STRUCTURED_OPS
 #define LINALG_STRUCTURED_OPS
 
 include "mlir/Dialect/Linalg/IR/LinalgBase.td"
 include "mlir/Dialect/Linalg/IR/LinalgInterfaces.td"
-include "mlir/Interfaces/ControlFlowInterfaces.td"
 include "mlir/Interfaces/DestinationStyleOpInterface.td"
 include "mlir/Interfaces/InferTypeOpInterface.td"
 include "mlir/Interfaces/SideEffectInterfaces.td"
 include "mlir/IR/OpAsmInterface.td"
 
 // Base Tablegen class for Linalg ops.
 // Linalg ops that correspond to library calls operate on ShapedType as their
 // first operands. These may be optionally followed by non-view operands
 // depending on the specific Linalg op.
 class LinalgStructuredBase_Op<string mnemonic, list<Trait> props>
   : Op<Linalg_Dialect, mnemonic, !listconcat([
        SingleBlockImplicitTerminator<"YieldOp">,
        DeclareOpInterfaceMethods<MemoryEffectsOpInterface>,
        DestinationStyleOpInterface,
        LinalgStructuredInterface,
-       RegionBranchOpInterface,
        ReifyRankedShapedTypeOpInterface], props)> {
   code structuredOpsBaseDecls = [{
     // Return whether the op accesses the iteration indices.
     bool hasIndexSemantics() {
       return !this->getBody()->getOps<IndexOp>().empty();
     }
 
     LogicalResult reifyResultShapes(OpBuilder &b,
         ReifiedRankedShapedTypeDims &reifiedReturnShapes) {
       return llvm::cast<LinalgOp>(getOperation()).reifyResultShapes(b,
           reifiedReturnShapes);
     }
-
-    void getSuccessorRegions(
-        std::optional<unsigned> index, ArrayRef<Attribute> operands,
-        SmallVectorImpl<RegionSuccessor> &regions) {
-      // Op has a region, but conceptually the control flow does not enter the
-      // region.
-    }
   }];
 }
 
 //===----------------------------------------------------------------------===//
 // Generic Linalg ops.
 //===----------------------------------------------------------------------===//
 
 def GenericOp : LinalgStructuredBase_Op<"generic", [