mm/zsmalloc: simplify zs_max_alloc_size handling

mm/zsmalloc: simplify zs_max_alloc_size handling

Commit 40f9fb8cffc6 ("mm/zsmalloc: support allocating obj with size of
ZS_MAX_ALLOC_SIZE") fixes a size calculation error that prevented
zsmalloc to allocate an object of the maximal size (ZS_MAX_ALLOC_SIZE).
I think however the fix is unneededly complicated.

This patch replaces the dynamic calculation of zs_size_classes at init
time by a compile time calculation that uses the DIV_ROUND_UP() macro
already used in get_size_class_index().

[[email protected]: use min_t]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Jerome Marchand <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Mahendran Ganesh <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>