aarch64 haskell: remove Simulator mention

No plans to resurrect Haskell simulation any more, so the comments are
mostly going to be confusing to people who come at this fresh.

Signed-off-by: Gerwin Klein <gerwin.klein@proofcraft.systems>

spec/haskell/src/SEL4/Kernel/VSpace/AARCH64.hs

@@ -850,15 +850,9 @@ performARMMMUInvocation i = withoutPreemption $ do
         InvokeVCPU _ -> fail "performARMMMUInvocation: not an MMU invocation"
     return $ []
 
-{- Simulator Support -}
-
 storePTE :: PPtr PTE -> PTE -> Kernel ()
 storePTE slot pte = do
     setObject slot pte
--- No simulator support currently available for RISCV, but this would be the
--- hook for PTEs:
--- doMachineOp $ storeWordVM (PPtr $ fromPPtr slot) $ wordFromPTE pte
-
 
 {- Unimplemented Boot Code Stubs -}