gpio: madera: Support Cirrus Logic Madera class codecs

gpio: madera: Support Cirrus Logic Madera class codecs

This adds support for the GPIOs on Cirrus Logic Madera class codecs.
Any pins not used for special functions (see the pinctrl driver) can be
used as general single-bit input or output lines. The number of available
GPIOs varies between codecs.

Change-Id: Id3473e03a0d0b3eea908d35f0ca2761bead3fb73
Signed-off-by: Nariman Poushin <nariman@opensource.wolfsonmicro.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>