xen/domain: fix late hwdom feature

Fix get_initial_domain_id() which returns hardware_domid and thus breaks
late hwdom feature [1].

[1] https://lore.kernel.org/xen-devel/a4c860d7-1fa0-43f4-8ae1-af59b7c6506f@xen.org/

Fixes: f147ccf2b3 ("xen/consoled: clean up console handling for PV shim")
Reported-by: Julien Grall <julien@xen.org>
Signed-off-by: Denis Mukhin <dmukhin@ford.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/common/domain.c

@@ -2404,7 +2404,7 @@ domid_t get_initial_domain_id(void)
     if ( pv_shim )
         return pv_shim_get_initial_domain_id();
 #endif
-    return hardware_domid;
+    return 0;
 }
 
 void freeze_domains(void)