context: Fixed negated permission string for allow and share options

It was solved partially in e0e1b20, but not for completely disallowed code path.
Steps to reproduce:
1. Run any flatpak with explicit --unshare option, e.g:
    [user@user-standardpc ~]$ flatpak run --unshare=network --command=bash io.gitlab.librewolf-community
2. Inside flatpak shell spawn any executable:
    [io.gitlab.librewolf-community ~]$ flatpak-spawn ls /
Result is:
error: Unknown option --noshare=network

common/flatpak-context.c

@@ -293,7 +293,7 @@ flatpak_permission_to_args (FlatpakPermission *permission,
     {
       /* Completely disallowed */
 
-      g_ptr_array_add (args, g_strdup_printf ("--no%s=%s", argname, name));
+      g_ptr_array_add (args, g_strdup_printf ("--%s=%s", noargname, name));
     }
 }