ACPI: i2c-scmi: don't use acpi_device_uid()

We recently removed the acpi_device_uid() interface because nobody
used it.  I don't think it's essential here either.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>