staging: dgap: Fix trailing whitespace in dgap_driver.c

This patch fixed trailing whitespace found by
checkpatch.pl in staging/dgap/dgap_driver.c
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>