staging: dgnc: Remove driver-wide state variable

This commit removes the driver's global state variable. This is ok
because the state was changed only once at the end of init phase thus
the future usage of this variable is pointless.

Signed-off-by: Konrad Zapalowicz <bergo.torino@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>