[mlir][tosa] Fix RFFT2D verifier for width=1 (#130279)

Current formula assumes width is a multiple of 2 but TOSA only requires
a power of 2, which 1 is.

Author: RoboTux

mlir/lib/Dialect/Tosa/IR/TosaOps.cpp

@@ -888,7 +888,7 @@ LogicalResult tosa::RFFT2dOp::verify() {
   // Output width dimension expected to be input_width / 2 + 1
   const int64_t outputWidth = outputType.getDimSize(2);
   if (!ShapedType::isDynamic(width) && !ShapedType::isDynamic(outputWidth) &&
-      (outputWidth - 1) * 2 != width)
+      (outputWidth != (width / 2) + 1))
     return emitOpError(
                "expected output width to be equal to input_width / 2 + 1, got ")
            << outputWidth;

mlir/test/Dialect/Tosa/ops.mlir

@@ -175,6 +175,13 @@ func.func @test_rfft2d(%arg0: tensor<13x8x16xf32>) -> (tensor<13x8x9xf32>, tenso
   return %0, %1 : tensor<13x8x9xf32>, tensor<13x8x9xf32>
 }
 
+// -----
+// CHECK-LABEL: rfft2d_width1
+func.func @test_rfft2d_width1(%arg0: tensor<1x1x1xf32>) -> (tensor<1x1x1xf32>, tensor<1x1x1xf32>) {
+  %0, %1 = tosa.rfft2d %arg0 : (tensor<1x1x1xf32>) -> (tensor<1x1x1xf32>, tensor<1x1x1xf32>)
+  return %0, %1 : tensor<1x1x1xf32>, tensor<1x1x1xf32>
+}
+
 // -----
 // CHECK-LABEL: rfft2d_with_local_bound
 func.func @test_rfft2d_with_local_bound(%arg0: tensor<13x8x16xf32>) -> (tensor<13x8x9xf32>, tensor<13x8x9xf32>) {