iio: proximity: sx_common: Add old register mapping

Older firmwares still send sensor configuration using a list of
registers with opaque values defined during sensor tuning.
sx9234 and sx9360 sensor on ACPI based devices are concerned.
More schema to configure the sensors will be needed to support devices
designed for windows, like Samsung Galaxy Book2.

Support schema is: "<_HID>.<register_name>". For instance
"STH9324,reg_adv_ctrl2" in:

    Scope (\_SB.PCI0.I2C2)
    {
        Device (SX28)
        {
            Name (_HID, "STH9324")  // _HID: Hardware ID
...
            Name (_DSD, Package (0x02)  // _DSD: Device-Specific Data
            {
                ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /*
Device Properties for _DSD */,
                Package (0x3F)
                {
...
                    Package (0x02)
                    {
                        "STH9324,reg_adv_ctrl2",
                        Zero
                    },`

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230211002421.3447060-1-gwendal@chromium.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>