staging: dgnc: dgnc_driver.h: Remove non-standard spinlock's macros

This patch removes non-standard spinlock's macros as they are no longer
used by this driver.

Signed-off-by: Roberta Dobrescu <roberta.dobrescu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>