xfs: sb_spino_align is not verified

It's just read in from the superblock and used without doing any
validity checks at all on the value.

Fixes: fb4f2b4e ("xfs: add sparse inode chunk alignment superblock field")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>