Dialog MCU: the HAL needs to change to not allow compiling out of the SPI code

The HALs for other MCUs do not allow compiling out SPI, they always expect that SPI and I2C code would always be compiled in. The drivers are written w.r.t. that expectation in mind.

The Dialog MCU hal needs to not allow compiling out of SPI similar to the other MCUs.

This issue is for discussion if other people think that we should not be doing that and we should allow compiling out individual interface codes like SPI.

Start by comparing the Dialog MCU HAL with the other MCU HALs, focusing on how SPI compilation is controlled and how the drivers depend on it. Resolve whether SPI should always be compiled in; done means the Dialog HAL follows the agreed policy consistently with the other MCU HALs.

Written by the indexing model from the issue text.