MAINTAINERS: add Youngjun Park as reviewer for SWAP

Recently, I have been actively contributing to the swap subsystem through
works such as swap-tier patches and flash friendly swap proposal. During
this process, I have consistently reviewed swap table code, some other
patches and fixed several bugs.

As I am already CC'd on many patches and maintaining active interest in
ongoing developments, I would like to officially add myself as a reviewer.
I am committed to contributing to the kernel community with greater
responsibility.

Link: https://lkml.kernel.org/r/20260226010739.3773838-1-youngjun.park@lge.com
Signed-off-by: Youngjun Park <youngjun.park@lge.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>