staging: unisys: visornic: Convert to using napi

Switch the visornic over to use napi.  Currently there is a kernel
thread that sits and waits on a wait queue to get notified of incoming
virtual interrupts. It would be nice if we could handle frame reception
using the standard napi processing instead.  This patch creates our napi
instance and has the rx thread schedule it

Given that the unisys hypervisor currently requires that queue servicing
be done by a polling loop that wakes up every 2ms, lets instead also
convert that to a timer, which is simpler, and allows us to remove all
the thread starting and stopping code.

Signed-off-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>