Fix bug in stm32-dma.adb: FIFO is improperly initialized.
Fix bug in stm32-dma.adb: FIFO is improperly initialized.

Fabien-Chouteau/Ada_Drivers_Library,ellamosi/Ada_BMP_Library,AdaCore/Ada_Drivers_Library,lambourg/Ada_Drivers_Library,simonjwright/Ada_Drivers_Library,Fabien-Chouteau/Ada_Drivers_Library,simonjwright/Ada_Drivers_Library,AdaCore/Ada_Drivers_Library