Revert "Makefile: add target to print generated files"

This reverts commit 9578f8cc.

The patch snuck in by accident without having been posted to
qemu-devel.  It's entirely redundant: existing target print-% already
serves the purpose.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180504054241.6833-1-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>