staging: dgnc: driver.c and .h: removes dgnc_driver_kzmalloc func

This patch removes the dgnc_driver_kzmalloc function from
driver.c and driver.h. A previous patch replaced all
dgnc_driver_kzmalloc function calls with kzalloc.

Signed-off-by: Lidza Louina <lidza.louina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>