fpga: dfl: fme: add power management support

fpga: dfl: fme: add power management support

This patch adds support for power management private feature under
FPGA Management Engine (FME). This private feature driver registers
a hwmon for power (power1_input), thresholds information, e.g.
(power1_max / crit / max_alarm / crit_alarm) and also read-only sysfs
interfaces for other power management information. For configuration,
user could write threshold values via above power1_max / crit sysfs
interface under hwmon too.

Signed-off-by: Luwei Kang <luwei.kang@intel.com>
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Moritz Fischer <mdf@kernel.org>