block: renumber QUEUE_FLAG_HW_WC

For the QUEUE_FLAG_HW_WC to actually work, it needs to have a separate
number from QUEUE_FLAG_FUA, doh.

Fixes: 43c9835b ("block: don't allow enabling a cache on devices that don't support it")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231226081524.180289-1-hch@lst.de


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