The reset and low power definitions for USART7/USART8 were correct, but not the primary enable registers. Fixes: https://github.com/libopencm3/libopencm3/issues/969
The reset and low power definitions for USART7/USART8 were correct, but not the primary enable registers. Fixes: https://github.com/libopencm3/libopencm3/issues/969