staging: zsmalloc: add/fix function comment

Add/fix the comment.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zram: remove the second argument of k[un]map_atomic()

Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Cong Wang <amwang@redhat.com>