[flang][openacc] Fix unparsing of bind clause on acc routine

unparsing for the bind clause was adding extra
parenthesis. This patch fixes that.

Reviewed By: razvanlupusoru

Differential Revision: https://reviews.llvm.org/D158210

Author: clementval

flang/lib/Parser/unparse.cpp

@@ -1890,10 +1890,8 @@ class UnparseVisitor {
   }
   void Unparse(const AccBindClause &x) {
     common::visit(common::visitors{
-                      [&](const Name &y) { Put('('), Walk(y), Put(')'); },
-                      [&](const ScalarDefaultCharExpr &y) {
-                        Put('('), Walk(y), Put(')');
-                      },
+                      [&](const Name &y) { Walk(y); },
+                      [&](const ScalarDefaultCharExpr &y) { Walk(y); },
                   },
         x.u);
   }

flang/test/Parser/acc-unparse.f90

@@ -76,3 +76,13 @@ subroutine acc_loop()
 ! CHECK: !$ACC LOOP GANG(STATIC:gangstatic,DIM:gangdim)
 
 end subroutine
+
+subroutine routine1()
+  !$acc routine bind("routine1_")
+! CHECK: !$ACC ROUTINE BIND("routine1_")
+end subroutine
+
+subroutine routine2()
+  !$acc routine(routine2) bind(routine2)
+! CHECK: !$ACC ROUTINE(routine2) BIND(routine2)
+end subroutine