xtables: Introduce and use common function to print val[/mask] arguments

xtables: Introduce and use common function to print val[/mask] arguments

There are number of places where argument is in val[/mask] format
printed in extensions and some of them may print corresponding symbolic
name.

By introducing common function for this task we eliminate custom code
parts in extensions to perform printing of arguments in required
formats.

Use xtables_print_mark_mask() helper for extensions without
symbolic name for val[/mask].

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>