uart1 deck driver freezes in case of Overrun error

[ataffanel]

If an overrun condition happens in the stm32 usart3, the peripheral used by the deck Uart1 port, it is not handled by the interrupt routine and so it is causing the interrupt to be called in an infinite loop freezing the Crazyflie. The overrun condition should be handled so that this does not happen.

On a side not, the overrun condition is going to cause loss of data, it would be useful to provide a function telling the user if that has happened.