ACPI: fan: Convert to use sysfs_emit_at() API

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

ACPI: fan: Add additional attributes for fine grain control

Add additional attributes, which helps in implementing algorithm in
the user space to optimize fan control. These attributes are presented
in the same directory as the existing performance state attributes.

Additional attributes:

1. Support of fine grain control
Publish support of presence of fine grain control so that fan speed
can be tuned correctly. This attribute is called "fine_grain_control".

2. fan speed
Publish the actual fan rpm in sysfs. Knowing fan rpm is helpful to
reduce noise level and use passive control instead. Also fan performance
may not be same over time, so the same control value may not be enough
to run the fan at a speed. So a feedback value of speed is helpful. This
sysfs attribute is called "fan_speed_rpm".

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

ACPI: fan: Separate file for attributes creation

Move the functionality of creation of sysfs attributes under acpi device
to a new file fan_attr.c. This cleans up the core fan code, which just
use thermal sysfs interface. The original fan.c is renamed to
fan_core.c.

No functional changes are expected.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>