i2400m: linkage to the networking stack

Implementation of the glue to the network stack so the WiMAX device
shows up as an Ethernet device.

Initially we shot for implementing a Pure IP device -- however, the
world seems to turn around Ethernet devices. Main issues were with the
ISC DHCP client and servers (as they don't understand types other than
Ethernet and Token Ring).

We proceeded to register with IANA the PureIP hw type, so that DHCP
requests could declare such. We also created patches to the main ISC
DHCP versions to support it. However, until all that permeates into
deployments, there is going to be a long time.

So we moved back to wrap Ethernet frames around the PureIP device. At
the time being this has overhead; we need to reallocate with space for
an Ethernet header. The reason is the device-to-host protocol
coalesces many network packets into a single message, so we can't
introduce Ethernet headers without overwriting valid data from other
packets.

Coming-soon versions of the firmware have this issue solved.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>