[mlir][vector][nfc] Move vector.splat test (llvm#145699)

Moves a test for vector.splat so that all invalid tests are grouped
together and easy to find.

Author: banach-space

mlir/test/Dialect/Vector/invalid.mlir

@@ -1667,13 +1667,6 @@ func.func @scan_unsupported_kind(%arg0: vector<2x3xf32>, %arg1: vector<3xf32>) -
   return %0#0 : vector<2x3xf32>
 }
 
-// -----
-
-func.func @invalid_splat(%v : f32) {
-  // expected-error@+1 {{invalid kind of type specified: expected builtin.vector, but found 'memref<8xf32>'}}
-  vector.splat %v : memref<8xf32>
-  return
-}
 
 // -----
 
@@ -1973,6 +1966,18 @@ func.func @flat_transpose_scalable(%arg0: vector<[16]xf32>) -> vector<[16]xf32>
   return %0 : vector<[16]xf32>
 }
 
+//===----------------------------------------------------------------------===//
+// vector.splat
+//===----------------------------------------------------------------------===//
+
+// -----
+
+func.func @vector_splat_invalid_result(%v : f32) {
+  // expected-error@+1 {{invalid kind of type specified: expected builtin.vector, but found 'memref<8xf32>'}}
+  vector.splat %v : memref<8xf32>
+  return
+}
+
 // -----
 
 // expected-note @+1 {{prior use here}}