i2400m: various functions for device management

This is a collection of functions used to control the device (plus a
few helpers).

There are utilities for handling TLV buffers, hooks on the device's
reports to act on device changes of state [i2400m_report_hook()], on
acks to commands [i2400m_msg_ack_hook()], a helper for sending
commands to the device and blocking until a reply arrives
[i2400m_msg_to_dev()], a few high level commands for manipulating the
device state, powersaving mode and configuration plus the routines to
setup the device once communication is established with it
[i2400m_dev_initialize()].

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