/drivers/staging/dgrp: Fixed warning unchecked sscanf return value

This patch solves the warning: unchecked sscanf return value from the script
checkpatch.pl for the file dgrp_sysfs.c

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>