BACKPORT: loop: Move loop_set_status_from_info() and friends up

So we can use it without forward declaration. This is a separate commit
to make it easier to verify that this is just a move, without functional
modifications.

Signed-off-by: Martijn Coenen <maco@android.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 62ab466ca881fe200c21aa74b65f8bd83ec482dc)
Bug: 148607611
Change-Id: I8c68ebbe65cbec476f9f2d4c1d60eb343e88bb56