staging: dgnc: delete dgnc_utils.c

There was just one function in it, and it duplicated what
msleep_interruptable() was doing, which is pointless, so delete it and
fix up the one calling site.

Cc: Lidza Louina <lidza.louina@gmail.com>
Cc: Mark Hounschell <markh@compro.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>