mm: zpool: add interfaces for object read/write APIs

Patch series "Switch zswap to object read/write APIs".

This patch series updates zswap to use the new object read/write APIs
defined by zsmalloc in [1], and remove the old object mapping APIs and the
related code from zpool and zsmalloc.


This patch (of 5):

Zsmalloc introduced new APIs to read/write objects besides mapping them. 
Add the necessary zpool interfaces.

Link: https://lkml.kernel.org/r/20250305061134.4105762-1-yosry.ahmed@linux.dev
Link: https://lkml.kernel.org/r/20250305061134.4105762-2-yosry.ahmed@linux.dev


Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>