rust: block: mq: use pin_init::zeroed() for tag_set

rust: block: mq: use pin_init::zeroed() for tag_set

Replace unsafe core::mem::zeroed() with pin_init::zeroed() for
blk_mq_tag_set initialization.

Signed-off-by: Ke Sun <sunke@kylinos.cn>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20260120083824.477339-4-sunke@kylinos.cn
Signed-off-by: Jens Axboe <axboe@kernel.dk>