Silence some warnings about unused function parameters

[martinling]

Fixes the following warnings:

../common/spi_common_all.c: In function 'spi_reset':
../common/spi_common_all.c:82:25: warning: unused parameter 'spi_peripheral' [-Wunused-parameter]
   82 | void spi_reset(uint32_t spi_peripheral)
      |                ~~~~~~~~~^~~~~~~~~~~~~~
../common/usart.c: In function 'usart_enable':
../common/usart.c:59:28: warning: unused parameter 'usart' [-Wunused-parameter]
   59 | void usart_enable(uint32_t usart)
      |                   ~~~~~~~~~^~~~~
../common/usart.c: In function 'usart_disable':
../common/usart.c:63:29: warning: unused parameter 'usart' [-Wunused-parameter]
   63 | void usart_disable(uint32_t usart)
      |                    ~~~~~~~~~^~~~~