mfd: madera: Add Madera core support for CS47L92

This patch adds all the core support and defines for the Cirrus
Logic CS42L92, CS47L92 and CS47L93 smart audio CODECs.

Registers or fields are named MADERA_* if it is part of the
common hardware platform and does not conflict with any other
Madera codecs. It is named CS47L15_* if it is unique to CS47L15
and conflicts with definitions on other codecs.

Signed-off-by: Stuart Henderson <stuarth@opensource.cirrus.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>