UPSTREAM: zsmalloc: remove extra cond_resched() in __zs_compact

(cherry-pick from commit 160a117f0864871ae1bab26554a985a1d2861afd)

Do not perform cond_resched() before the busy compaction loop in
__zs_compact(), because this loop does it when needed.

Bug: 25951511

Change-Id: I3b20b46f3a4fb44a2bf6ccb17264acf30deb7111
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>