wpanusb: enhancement for beagleconnect freedom gateway

* get valid channels from device
* disable IEEE802154_HW_PROMISCUOUS mode to  disable error is kernel logs
* with the changes Sub-G(with zephyr patch for PA) works without issues
* 2.4G fails at setting channel
* add simple rmmod script to remove assosciated modules, useful during
  driver testing

SubG host(valid channels received from gateway device):

vaishnav@spectre:~/freedom/wpanusb$ sudo ./scripts/modprobe.sh
vaishnav@spectre:~/freedom/wpanusb$ sudo scripts/lowpan.sh 2 1
Using phy phy0 channel 1 PAN ID 0xabcd
IP: 2001:db8::2/64 Short: 0xbee2
Cannot find device "lowpan0"
vaishnav@spectre:~/freedom/wpanusb$ ping6 2001:db8::1
PING 2001:db8::1(2001:db8::1) 56 data bytes
64 bytes from 2001:db8::1: icmp_seq=1 ttl=64 time=67.7 ms
64 bytes from 2001:db8::1: icmp_seq=2 ttl=64 time=39.2 ms
64 bytes from 2001:db8::1: icmp_seq=3 ttl=64 time=40.5 ms
64 bytes from 2001:db8::1: icmp_seq=4 ttl=64 time=38.9 ms
64 bytes from 2001:db8::1: icmp_seq=5 ttl=64 time=38.9 ms...

Add wpan-next changes and BeagleConnect device

Add wpan-next and BeagleConnect config

Add BeagleConnect device
Add channels 0-10 to default capabilities

Signed-off-by: Erik Larson <erik@statropy.com>

Add a wireshark test script
Add html file for http server test

Put wpan0 down before config
fix typo

Change to temp VID/PID
Add test python client/server scripts
Add more config options to lowpan setup script
Add debug messages

Call kfree() after USB control msg and clean up debug messages

The patch adds Linux kernel driver for wpanusb 802.15.4 USB devices
implementing IEEE802.15.4 over USB protocol specified here:
https://github.com/zephyrproject-rtos/zephyr/blob/master/samples/
net/wpanusb/wpan-radio-spec.txt

The driver is basically reworked atusb driver with interface
changed to be more general, suitable for all 802.15.4 hardware.