[Ada] Remove excessive guard in detection of access-to-variable objects

[Pierre-Marie de Rodat via Gcc-patches]

It is safe to call Is_Access_Variable without calling
Is_Access_Object_Type before. Compiler cleanup only; semantics is
unaffected.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * sem_util.adb (Is_Variable): Remove excessive guard.
diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -21896,7 +21896,6 @@ package body Sem_Util is
               or else (K = E_Component
                         and then not In_Protected_Function (E))
               or else (Present (Etype (E))
-                        and then Is_Access_Object_Type (Etype (E))
                         and then Is_Access_Variable (Etype (E))
                         and then Is_Dereferenced (N))
               or else K = E_Out_Parameter