realtek: HPE 1920 8G PoE+ 180W move fans to hwmon

The GPIO numbering has changed and is not stable. As a result fan
control via gpio_switch is broken, resulting in errors:
    "export_store: invalid GPIO 456"

Move to using hwmon and gpio-fan. This is by adding gpio_fan_array to
DTS and kmod-hwmon-gpiofan to DEVICE_PACKAGES.

In combination with the new rtl8231 gpio driver the default fan
behaviour will be maximum fan speed.

Bump compat value to 1.1 due to existing config in /etc/config/system
via gpio_switch. Also notify in device compat that fan is now going to
be at bootloader setting (maximum in this case) by default unless turned
down.

Signed-off-by: Evan Jobling <evan@jobling.au>
Link: https://github.com/openwrt/openwrt/pull/17605


Signed-off-by: Sander Vanheule <sander@svanheule.net>