staging: dgnc: remove unused variable named rawreadok

This patch removes the variable rawreadok since it is only intialized
but not used in any of the driver functions.

Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>