#810 Incorrect constants STM32_DAC1_CHx_DMA_CHN for STM32F7

[Adam]

The constants STM32_DAC1_CH1_DMA_CHN and STM32_DAC1_CH2_DMA_CHN in os/hal/ports/STM32/STM32F7xx/stm32_registry.h are incorrect. The DAC uses DMA1 streams 5 and 6 (per reference manual table 27), both on channel 7, but the constants are currently 0x00070000 and 0x00700000, as though it used streams 4 and 5. Instead they should be 0x00700000 and 0x07000000 (for ch1/ch2 respectively) to map to streams 5 and 6.

[Giovanni Di Sirio]

Fixed in repository, will be fixed in 16.1.7.