Fixed unused variable compiler warning in stm32f4xx_ll_adc.h for function LL_ADC_DMA_GetRegAddr

[gerardhale]

Fixed unused variable compiler warning in stm32f4xx_ll_adc.h for function LL_ADC_DMA_GetRegAddr when ADC_MULTIMODE_SUPPORT not defined

we are compiling the stm32f4xx_hal_drvier as a library to test our HAL on the stm32f401 dev board

Building CXX object hal/CMakeFiles/hal_platfor...m32f401.dir/platforms/stm32f4_hal/src/HalGpioF4.cpp.obj In file included from ../../platforms/stm32f4_hal/stm32f4xx_hal_driver/Inc/stm32f4xx_hal_adc.h:31, from ../../platforms/stm32f4_hal/custom/inc/stm32f4xx_hal_conf.h:300, from ../../platforms/stm32f4_hal/stm32f4xx_hal_driver/Inc/stm32f4xx_hal.h:29, from ../../hal/platforms/stm32f4_hal/src/HalGpioF4.cpp:9: ../../platforms/stm32f4_hal/stm32f4xx_hal_driver/Inc/stm32f4xx_ll_adc.h: In function 'uint32_t LL_ADC_DMA_GetRegAddr(ADC_TypeDef*, uint32_t)': ../../platforms/stm32f4_hal/stm32f4xx_hal_driver/Inc/stm32f4xx_ll_adc.h:1880:76: warning: unused parameter 'Register' [-Wunused-parameter]

A clear and concise description of what the bug is.

How to reproduce the bug (skip if none) compile the hal_driver without defining ADC_MULTIMODE_SUPPORT and using -Wunused-parameter