zsmalloc: add Kconfig for enabling page table method

zsmalloc: add Kconfig for enabling page table method

Zsmalloc has two methods 1) copy-based and 2) pte based to
access objects that span two pages.
You can see history why we supported two approach from [1].

But it was bad choice that adding hard coding to select arch
which want to use pte based method because there are lots of
SoC in an architecure and they can have different cache size,
CPU speed and so on so it would be better to expose it to user
as selectable Kconfig option like Andrew Morton suggested.

[1] https://lkml.org/lkml/2012/7/11/58

Acked-by: Nitin Gupta <ngupta@vflare.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>