STM32 BDMAv1 driver.

Driver capability:

- The driver supports the "basic" DMA controller.

The file registry must export:

STM32_BDMAn_CHx_HANDLER     - Vector name for IRQ "x" (1..7). If the macro
                              is not exported then the ISR is not declared.
STM32_BDMAn_CHx_NUMBER      - Vector number for IRQ "x" (1..7).