Revert: xfs: fix _xfs_buf_find oops on blocks beyond the filesystem end

This reverts commit a5604073 which was
commit eb178619 upstream.

It has been reported to cause problems:
	http://bugzilla.redhat.com/show_bug.cgi?id=909602



Acked-by: Ben Myers <bpm@sgi.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Cc: Brian Foster <bfoster@redhat.com>
Cc: CAI Qian <caiqian@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>