Staging: lustre: fix line over 80 characters in dt_object.c

Fixes a line over 80 characters warining in
lustre/lustre/obdclass/dt_object.c that was found by the
checkpatch.pl tool.

Signed-off-by: Zoltán Lajos Kis <zoltan.lajos.kis@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>