swsusp: don't pass a stack address to blkdev_get_by_path

holder is just an on-stack pointer that can easily be reused by other calls,
replace it with a static variable that doesn't change.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-12-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>