HID: asus: Implement Fn+F5 fan control key handler

HID: asus: Implement Fn+F5 fan control key handler

On Asus ROG laptops, the Fn+F5 key (HID code 0xae) is used to cycle
through fan modes. This key press needs to be forwarded to the asus-wmi
driver to actually change the fan mode.

Add ASUS_FAN_CTRL_KEY_CODE define and implement the handler in
asus_raw_event() to send WMI events when this key is pressed.

When asus-wmi successfully handles the event, it is blocked from reaching
userspace. If asus-wmi is unavailable or fails, the event is passed to
userspace via evdev, allowing userspace implementations of fan control.

Tested on Asus ROG G14/G15 series laptops.

Reviewed-by: Denis Benato <benato.denis96@gmail.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Ionut Nechita <ionut_n2001@yahoo.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>