spi: spidev: Add device to spidev device tree compatibility list

Entries are needed in the spidev ID list to configure configure it from a
device tree. Add entry for the following device:
- "ge,achc" :  GE Healthcare USB Management Controller

The USB Management Controller does not expose USB to the host, but acts as
an offload engine, communicating with specific USB based data acquisition
devices which are connected to it, extracting the required data and
providing it to the host via other methods. SPI is used as an out-of-band
configuration channel.

Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.co.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>