[flang][coarray] Unexpected error: 'fir.store' op store value type must match memory reference type

```
% cat r.f90
```
```
class(*),allocatable :: a[:]
allocate(real::a[1:*])
end
```
```
% flang -c -fcoarray r.f90
warning: Support for multi image Fortran features is still experimental and in development.
error: loc("r.f90":2:2): 'fir.store' op store value type must match memory reference type
error: verification of lowering to FIR failed
```