staging: dgnc: convert to wait_event_interruptible_timeout

This patch makes use of wait_event_interruptible_timeout to achieve
timeout functionality.This is a TODO mentiond in the comment which is also
removed.It also aligns with what the function is supposed to do as in the
comments.

Signed-off-by: Hari Prasath Gujulan Elango <hgujulan@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>