Staging: lustre: fix braces are not necessary in dt_object.c

Fixes a braces {} are not necessary for any arm of this statement
warning 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>