tree-wide: Use autoptr for OstreeKernelArgs

Much nicer looking.  Prep for more cleanup from
https://github.com/projectatomic/rpm-ostree/pull/1013

Closes: #1302
Approved by: peterbaouoft

src/libostree/ostree-kernel-args.c

@@ -81,7 +81,7 @@ _ostree_kernel_args_new (void)
 }
 
 void
-_ostree_kernel_arg_autofree (OstreeKernelArgs *kargs)
+_ostree_kernel_args_free (OstreeKernelArgs *kargs)
 {
   if (!kargs)
     return;
@@ -90,12 +90,6 @@ _ostree_kernel_arg_autofree (OstreeKernelArgs *kargs)
   g_free (kargs);
 }
 
-void
-_ostree_kernel_args_cleanup (void *loc)
-{
-  _ostree_kernel_arg_autofree (*((OstreeKernelArgs**)loc));
-}
-
 void
 _ostree_kernel_args_replace_take (OstreeKernelArgs   *kargs,
                                   char               *arg)