hwmon: Remove smm665 driver

SMM665 and related chips are power controller/sequencer chips from
Summit Microelectronics. The company was acquired by Qualcomm in 2012,
and support for the chip series stopped.

The chips are long since gone from active use, making the driver
unsupportable and just consuming space and compile time. Remove it.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>