fs: move the bdex_statx call to vfs_getattr_nosec

fs: move the bdex_statx call to vfs_getattr_nosec

Currently bdex_statx is only called from the very high-level
vfs_statx_path function, and thus bypassing it for in-kernel calls
to vfs_getattr or vfs_getattr_nosec.

This breaks querying the block ѕize of the underlying device in the
loop driver and also is a pitfall for any other new kernel caller.

Move the call into the lowest level helper to ensure all callers get
the right results.

Fixes: 2d985f8c6b91 ("vfs: support STATX_DIOALIGN on block devices")
Fixes: f4774e92aab8 ("loop: take the file system minimum dio alignment into account")
Reported-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250417064042.712140-1-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>