[flang][openacc] Relax type check for private recipe on acc.serial (#68814)

The check was already relax on `acc.parallel` but not on `acc.serial`.
This patch makes is consistent.

Author: clementval

flang/test/Lower/OpenACC/acc-private.f90

@@ -270,6 +270,10 @@ subroutine acc_private_allocatable_array(a, n)
   do i = 1, n
     a(i) = i
   end do
+
+  !$acc serial private(a)
+  a(i) = 1
+  !$acc end serial
 end subroutine
 
 ! CHECK-LABEL: func.func @_QPacc_private_allocatable_array(
@@ -278,7 +282,8 @@ subroutine acc_private_allocatable_array(a, n)
 ! HLFIR: %[[BOX:.*]] = fir.load %[[DECLA_A]]#1 : !fir.ref<!fir.box<!fir.heap<!fir.array<?xi32>>>>
 ! HLFIR: %[[BOX_ADDR:.*]] = fir.box_addr %[[BOX]] : (!fir.box<!fir.heap<!fir.array<?xi32>>>) -> !fir.heap<!fir.array<?xi32>>
 ! HLFIR: %[[PRIVATE:.*]] = acc.private varPtr(%[[BOX_ADDR]] : !fir.heap<!fir.array<?xi32>>) bounds(%{{.*}}) -> !fir.heap<!fir.array<?xi32>> {name = "a"}
-! HLFIR: acc.parallel private(@privatization_box_heap_Uxi32 -> %[[PRIVATE]] : !fir.heap<!fir.array<?xi32>>) {
+! HLFIR: acc.parallel private(@privatization_box_heap_Uxi32 -> %[[PRIVATE]] : !fir.heap<!fir.array<?xi32>>)
+! HLFIR: acc.serial private(@privatization_box_heap_Uxi32 -> %{{.*}} : !fir.heap<!fir.array<?xi32>>)
 
 subroutine acc_private_pointer_array(a, n)
   integer, pointer :: a(:)

mlir/lib/Dialect/OpenACC/IR/OpenACC.cpp

@@ -620,7 +620,7 @@ Value ParallelOp::getDataOperand(unsigned i) {
 LogicalResult acc::ParallelOp::verify() {
   if (failed(checkSymOperandList<mlir::acc::PrivateRecipeOp>(
           *this, getPrivatizations(), getGangPrivateOperands(), "private",
-          "privatizations", false)))
+          "privatizations", /*checkOperandType=*/false)))
     return failure();
   if (failed(checkSymOperandList<mlir::acc::ReductionRecipeOp>(
           *this, getReductionRecipes(), getReductionOperands(), "reduction",
@@ -650,7 +650,7 @@ Value SerialOp::getDataOperand(unsigned i) {
 LogicalResult acc::SerialOp::verify() {
   if (failed(checkSymOperandList<mlir::acc::PrivateRecipeOp>(
           *this, getPrivatizations(), getGangPrivateOperands(), "private",
-          "privatizations")))
+          "privatizations", /*checkOperandType=*/false)))
     return failure();
   if (failed(checkSymOperandList<mlir::acc::ReductionRecipeOp>(
           *this, getReductionRecipes(), getReductionOperands(), "reduction",