Switch back to MonoTimer from HAL

According to stm32-rs/stm32f3xx-hal#247 it got
removed accidentially and has been resurrected. There is no need for the
local copy from here.

Author: sirhcel

src/11-usart/auxiliary/src/lib.rs

@@ -9,14 +9,12 @@ pub use cortex_m::{asm::bkpt, iprint, iprintln, peripheral::ITM};
 pub use cortex_m_rt::entry;
 pub use stm32f3_discovery::stm32f3xx_hal::pac::usart1;
 
-pub mod monotimer;
-
 use stm32f3_discovery::stm32f3xx_hal::{
     prelude::*,
     serial::Serial,
     pac::{self, USART1},
+    timer::MonoTimer,
 };
-use monotimer::MonoTimer;
 
 pub fn init() -> (&'static mut usart1::RegisterBlock, MonoTimer, ITM) {
     let cp = cortex_m::Peripherals::take().unwrap();