zsmalloc: remove unnecessary insertion/removal of zspage in compaction

zsmalloc: remove unnecessary insertion/removal of zspage in compaction

In putback_zspage, we don't need to insert a zspage into list of zspage
in size_class again to just fix fullness group. We could do directly
without reinsertion so we could save some instuctions.

Reported-by: Heesub Shin <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Dan Streetman <[email protected]>
Cc: Seth Jennings <[email protected]>
Cc: Ganesh Mahendran <[email protected]>
Cc: Luigi Semenzato <[email protected]>
Cc: Gunho Lee <[email protected]>
Cc: Juneho Choi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>