platform/x86: mlx-platform: Add mlxreg-fan platform driver activation

Add mlxreg-fan platform driver activation. FAN driver uses the same regmap
infrastructure as others Mellanox platform drivers. Specific registers
description for default FAN platform data configuration are added to
mlx-platform. There are the registers for tachometers reading, PWM
control and FAN ownership control. The last one has a default value,
which is set at initialization time through the regmap infrastructure,
which is necessary for moving FAN control ownership from hardware to
software.

Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>