wimax/i2400m: fix device getting stuck in IDLE mode

The i2400m, when conected, will negotiate with the WiMAX basestation
to put the link in IDLE mode when it is not being used. Upon RX/TX
traffic, the link has to be restablished and that might require some
crypto handshakes and maybe a DHCP renew.

This process might take up to 20 (!) seconds and in some cases we were
seeing network watchdog warnings that weren't needed.

So the network watchdog timeout is updated to be slightly above that
20s threshold. As well, the driver itself will double check if the
device is stuck in IDLE mode -- if that happens, the device will be
reset (in this case the queue is also woken up to remove bogus--once
the device is reset--warnings).

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>