HSI: cmt_speech: Add cmt-speech driver

HSI: cmt_speech: Add cmt-speech driver

Introduces the cmt-speech driver, which implements
a character device interface for transferring speech
data frames over HSI/SSI.

The driver is used to exchange voice/speech data between
the Nokia N900/N950/N9's modem and its cpu.

Signed-off-by: Kai Vehmanen <kai.vehmanen@nokia.com>
Signed-off-by: Carlos Chinea <carlos.chinea@nokia.com>
Signed-off-by: Joni Lapilainen <joni.lapilainen@gmail.com>
Since the original driver has been written for 2.6.28 some
build fixes and general cleanups have been added by me:

 * fix build for 4.0 kernel
 * replace GFP_ATOMIC with GFP_KERNEL in cs_alloc_cmds()
 * add sanity check for CS_SET_WAKELINE ioctl
 * cleanup driver initialisation
 * rename driver to cmt-speech to be consistent with
   ssi-protocol driver
 * move cs-protocol.h to include/uapi/linux/hsi, since
   it describes a userspace API
 * replace hardcoded channels numbers with values provided
   via the HSI framework (e.g. coming from DT)

Acked-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Tested-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sre@kernel.org>