fs/ntfs3: remove unnecessary NULL check

This code triggers a Smatch warning:

    fs/ntfs3/fsntfs.c:1606 ntfs_bio_fill_1()
    warn: variable dereferenced before check 'bio' (see line 1591)

The "bio" pointer cannot be NULL so there is no need to check.
Originally there was more extensive NULL checking but it was removed
because bio_alloc() will never fail if it is allowed to sleep.

Remove this check as well.

Fixes: 39146b6f

 ("ntfs3: remove ntfs_alloc_bio")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220128140922.GA29766@kili


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