zram: switch to new zsmalloc object mapping API

zram: switch to new zsmalloc object mapping API

Use new read/write zsmalloc object API.  For cases when RO mapped object
spans two physical pages (requires temp buffer) compression streams now
carry around one extra physical page.

Link: https://lkml.kernel.org/r/20250303022425.285971-16-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>