block: Directly use ida_alloc()/free()

Use ida_alloc()/ida_free() instead of
ida_simple_get()/ida_simple_remove().
The latter is deprecated and more verbose.

Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20220615081816.4342-1-liubo03@inspur.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>