treewide: remove stale instances of struct device ...

We call it struct device_d, any instances of struct device are likely
left-over code after porting from Linux.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

i2c: introduce device_i2c_driver() macro ...

Add macro and dependency to avoid boilerplate code. Since now simple
i2c drivers only have to include the i2c.h header and call the
device_i2c_driver() macro to register a i2c device driver.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

gpio: Port SX150x driver from Linux ...

Add a very abridged version of SX150x driver from Linux. New, "pinctrl"
version of the driver was used as a base. As it was already mentioned
this driver supports very limited amount of the original functionality,
and the following are the features that were dropped:
     - Interrupt support
     - Support for any chip other that SX150x (due to lack of HW to test
       with)
     - Any pinctlr-like functions: pull-up/pull-down, open-drain,
       etc. configuration

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>