wireless/ieee802154: Adds sniffer back to I8SAK app

Approved-by: Gregory Nutt <gnutt@nuttx.org>

wireless/wapi: wpa_driver_wext_associate() now accepts a configuration parameter that can be used to specify the wireless properties.  nshlib:  NSH now has configuration options to select the wireless properties.  It builds the configuration structure and passes this to wpa_driver_wext_associate() so that it will setwork the network as configured.

Move wireless/wext into wireless/wapi/src.  Update some naming for better follow the NuttX coding style.

wireless/ieee802154: msdu_length in meta data converted to a seperate length argument

Approved-by: Gregory Nutt <gnutt@nuttx.org>

wireless/ieee802154:  Removes libradio to coincide with removal of ioctl with radio

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Moves all functionality from libradio to libmac

netutils/dhcpc:  Make the network device name a configuration option.  Was hardcoded to eth0 but may, instead, need to be wlan0

I need to look at the registers that are at or around 0xe000ef90.  Using mw and xd, I see that nsh does not support pointers greater than 0x7fffffff.  A quick look at the source shows that the pointers for those two commands are set with calls to strtol() rather than strtoul().  Changing the two pointer-setting instances to strtoul() fixes the problem, at least for my architecture/config.

wireless/ieee802154/libmac:  Finishes all defined MAC IOCTL helpers (thre are a few that are not defined).