staging: dgnc: rephrase comment

Rephrase comment to explain original intention of function.

CC: Lidza Louina <lidza.louina@gmail.com>
CC: Mark Hounschell <markh@compro.net>
Suggested-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Seunghun Lee <waydi1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>