Most UART drivers don't implement the full `modm::Uart` interface

Many drivers don't implement the full [`modm::Uart`](https://github.com/modm-io/modm/blob/4d692276573720d59642f262d8a8b0019b4d5829/src/modm/architecture/interface/uart.hpp) interface, e.g. `clearError()` is only present in the STM32 and the RTT driver.