corrected bug in FIFO SRC register queries
corrected bug in FIFO SRC register queries

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