zsmalloc: set default zspage chain size to 8

This changes key characteristics (pages per-zspage and objects per-zspage)
of a number of size classes which in results in different pool
configuration.  With zspage chain size of 8 we have more size clases
clusters (123) and higher huge size class watermark (3632 bytes).

Please read zsmalloc documentation for more details.

Link: https://lkml.kernel.org/r/20230118005210.2814763-5-senozhatsky@chromium.org


Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>