spi: spidev: Add an entry for the gocontroll moduline module slot

The main point of the Moduline series of embedded controllers is its
ecosystem of IO modules, these are currently operated through the spidev
interface. Ideally there will be a full dedicated driver in the future.

Add the gocontroll moduline-module-slot device to enable the required
spidev interface.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
Link: https://patch.msgid.link/20250226-initial_display-v2-12-23fafa130817@gocontroll.com


Signed-off-by: Mark Brown <broonie@kernel.org>