Revert "[flang][openacc] Add clause validity tests for the update directive"

This reverts commit e460654.

Author: clementval

flang/lib/Semantics/check-acc-structure.cpp

@@ -201,8 +201,6 @@ void AccStructureChecker::Leave(const parser::OpenACCStandaloneConstruct &x) {
     CheckRequireAtLeastOneOf();
     break;
   case llvm::acc::Directive::ACCD_update:
-    // Restriction - line 2636
-    CheckRequireAtLeastOneOf();
     // Restriction - 2301
     CheckOnlyAllowedAfter(llvm::acc::Clause::ACCC_device_type,
         updateOnlyAllowedAfterDeviceTypeClauses);

flang/test/Semantics/acc-clause-validity.f90

@@ -138,37 +138,9 @@ program openacc_clause_validity
   !ERROR: Unmatched PARALLEL directive
   !$acc end parallel
 
-  !ERROR: At least one of DEVICE, HOST, SELF clause must appear on the UPDATE directive
-  !$acc update
-
   !$acc update self(a, f) host(g) device(h)
 
-  !$acc update host(aa) async(1)
-
-  !$acc update device(bb) async(async1)
-
-  !ERROR: At most one ASYNC clause can appear on the UPDATE directive
-  !$acc update host(aa, bb) async(1) async(2)
-
-  !$acc update self(bb, cc(:)) wait(1)
-
-  !$acc update device(aa, bb, cc) wait(wait1)
-
-  !$acc update host(aa) host(bb) device(cc) wait(1,2)
-
-  !$acc update device(aa, cc) wait(wait1, wait2)
-
-  !$acc update device(aa) device_type(*) async
-
-  !$acc update host(bb) device_type(*) wait
-
-  !$acc update self(cc) device_type(1,2) async device_type(3) wait
-
-  !ERROR: At most one IF clause can appear on the UPDATE directive
-  !$acc update device(aa) if(.true.) if(ifCondition)
-
-  !ERROR: At most one IF_PRESENT clause can appear on the UPDATE directive
-  !$acc update device(bb) if_present if_present
+  !$acc update device(i) device_type(*) async
 
   !ERROR: Clause IF is not allowed after clause DEVICE_TYPE on the UPDATE directive
   !$acc update device(i) device_type(*) if(.TRUE.)