extcon: intel-cht-wc: Report RID_A for ACA adapters

Make cht_wc_extcon_get_id() report RID_A for ACA adapters, instead of
reporting ID_FLOAT.

According to the spec. we should read the USB-ID pin ADC value
to determine the resistance of the used pull-down resister and
then return RID_A / RID_B / RID_C based on this. But all "Accessory
Charger Adapter"s (ACAs) which users can actually buy always use
a combination of a charging port with one or more USB-A ports, so
they should always use a resistor indicating RID_A. But the spec
is hard to read / badly-worded so some of them actually indicate
they are a RID_B ACA even though they clearly are a RID_A ACA.

To workaround this simply always return INTEL_USB_RID_A, which
matches all the ACAs which users can actually buy.

Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>