[flang][acc] Create UseDeviceOp for both results of hlfir.declare (#148017)
A sample such as
```
program test
integer :: N = 100
real*8 :: b(-1:N)
!$acc data copy(b)
!$acc host_data use_device(b)
call vadd(b)
!$acc end host_data
!$acc end data
end
```
is lowered to
```
%13:2 = hlfir.declare %11(%12) {uniq_name = "_QFEb"} : (!fir.ref<!fir.array<?xf64>>, !fir.shapeshift<1>) -> (!fir.box<!fir.array<?xf64>>, !fir.ref<!fir.array<?xf64>>)
%14 = acc.copyin var(%13#0 : !fir.box<!fir.array<?xf64>>) -> !fir.box<!fir.array<?xf64>> {dataClause = #acc<data_clause acc_copy>, name = "b"}
acc.data dataOperands(%14 : !fir.box<!fir.array<?xf64>>) {
%15 = acc.use_device var(%13#0 : !fir.box<!fir.array<?xf64>>) -> !fir.box<!fir.array<?xf64>> {name = "b"}
acc.host_data dataOperands(%15 : !fir.box<!fir.array<?xf64>>) {
fir.call @_QPvadd(%13#1) fastmath<contract> : (!fir.ref<!fir.array<?xf64>>) -> ()
acc.terminator
}
acc.terminator
}
acc.copyout accVar(%14 : !fir.box<!fir.array<?xf64>>) to var(%13#0 : !fir.box<!fir.array<?xf64>>) {dataClause = #acc<data_clause acc_copy>, name = "b"}
```
Note that while the use_device clause is applied to %13#0, the argument
passed to vadd is %13#1. To avoid problems later in lowering, this
change additionally applies the use_device clause to %13#1, so that the
resulting MLIR is
```
%13:2 = hlfir.declare %11(%12) {uniq_name = "_QFEb"} : (!fir.ref<!fir.array<?xf64>>, !fir.shapeshift<1>) -> (!fir.box<!fir.array<?xf64>>, !fir.ref<!fir.array<?xf64>>)
%14 = acc.copyin var(%13#0 : !fir.box<!fir.array<?xf64>>) -> !fir.box<!fir.array<?xf64>> {dataClause = #acc<data_clause acc_copy>, name = "b"}
acc.data dataOperands(%14 : !fir.box<!fir.array<?xf64>>) {
%15 = acc.use_device var(%13#0 : !fir.box<!fir.array<?xf64>>) -> !fir.box<!fir.array<?xf64>> {name = "b"}
%16 = acc.use_device varPtr(%13#1 : !fir.ref<!fir.array<?xf64>>) -> !fir.ref<!fir.array<?xf64>> {name = "b"}
acc.host_data dataOperands(%15, %16 : !fir.box<!fir.array<?xf64>>, !fir.ref<!fir.array<?xf64>>) {
fir.call @_QPvadd(%13#1) fastmath<contract> : (!fir.ref<!fir.array<?xf64>>) -> ()
acc.terminator
}
acc.terminator
}
acc.copyout accVar(%14 : !fir.box<!fir.array<?xf64>>) to var(%13#0 : !fir.box<!fir.array<?xf64>>) {dataClause = #acc<data_clause acc_copy>, name = "b"}
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