[OpenMP][MLIR] Add assembly format for master op

Reviewed By: SouraVX, kiranktp

Differential Revision: https://reviews.llvm.org/D87549

mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td

@@ -138,6 +138,8 @@ def MasterOp : OpenMP_Op<"master"> {
   }];
 
   let regions = (region AnyRegion:$region);
+
+  let assemblyFormat = "$region attr-dict";
 }
 
 //===----------------------------------------------------------------------===//

mlir/test/Dialect/OpenMP/ops.mlir

@@ -8,10 +8,11 @@ func @omp_barrier() -> () {
 
 func @omp_master() -> () {
   // CHECK: omp.master
-  "omp.master" ()({
+  omp.master {
     // CHECK: omp.terminator
     omp.terminator
-  }):()->()
+  }
+
   return
 }