hwmon: (gxp-fan-ctrl) Add GXP fan controller

The GXP SoC can support up to 16 fans through the interface provided by
the CPLD. The current support is limited to 8 fans. The fans speeds are
controlled via 8 different PWMs which can vary in value from  0-255. The
fans are also capable of reporting if they have failed to the CPLD which
in turn reports the status to the GXP SoC.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
Link: https://lore.kernel.org/r/20230103203654.59322-2-nick.hawkins@hpe.com


[groeck: Improved alignment of defined, added missing include linux/bits.h]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>