HID: i2c-hid: Remove runtime power management

Runtime power management in i2c-hid brings lots of issues, such as:
- When transitioning from display manager to desktop session, i2c-hid
was closed and opened, so the device was set to SLEEP and ON in a short
period. Vendors confirmed that their devices can't handle fast ON/SLEEP
command because Windows doesn't have this behavior.

- When rebooting, i2c-hid was closed, and the driver core put the device
back to full power before shutdown. This behavior also triggers a quick
SLEEP and ON commands that some devices can't handle, renders an
unusable touchpad after reboot.

- Most importantly, my power meter reports little to none energy saving
when i2c-hid is runtime suspended.

So let's remove runtime power management since there is no actual
benefit.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>