staging: dgap: Fix trailing whitespace in dgap_sysfs.h

This patch fixed trailing whitespace found by checkpatch.pl
in staging/dgap/dgap_sysfs.h

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Lidza Louina <Lidza.Louina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>