block: remove bogus comments in __bio_add_pc_page

We are never called with file system pages by defintions for the
passthrough interface, and we also never undo any addition later
these days.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed