memory: Clean up how mtree_info() prints

memory: Clean up how mtree_info() prints

mtree_info() takes an fprintf()-like callback and a FILE * to pass to
it, and so do its helper functions.  Passing around callback and
argument is rather tiresome.

Its only caller hmp_info_mtree() passes monitor_printf() cast to
fprintf_function and the current monitor cast to FILE *.

The type-punning is technically undefined behaviour, but works in
practice.  Clean up: drop the callback, and call qemu_printf()
instead.

Signed-off-by: Markus Armbruster <[email protected]>
Reviewed-by: Dr. David Alan Gilbert <[email protected]>
Message-Id: <20190417191805[email protected]>