I'm trying to write a driver for an SPI peripheral.
west says:
```
../ncs/zephyr/samples/sensor/mydriver/prj.conf:5: warning: attempt to assign the value 'y' to the undefined symbol MYDRIVER
```
prj.conf is:
```
CONFIG_SENSOR=y
CONFIG_SPI=y
CONFIG_I2C=n
CONFIG_MYDRIVER=y
```
I've looked at other drivers but have not seen where their main CONFIG_ symbol is defined.
Where else to look pls?