Apply some clippy suggestions

Author: Sh3Rm4n

src/adc.rs

@@ -348,7 +348,7 @@ where
         // NOTE: Software is allowed to set ADSTP only when ADSTART=1 and ADDIS=0
         // (ADC is enabled and eventually converting a regular conversion and there is no
         // pending request to disable the ADC)
-        if self.adc.cr.read().addis().bit() == false
+        if !self.adc.cr.read().addis().bit()
             && (self.adc.cr.read().adstart().bit() || self.adc.cr.read().jadstart().bit())
         {
             self.adc.cr.modify(|_, w| w.adstp().stop());
@@ -385,7 +385,7 @@ where
     }
 
     fn wait_adc_clk_cycles(&self, cycles: u32, clocks: Clocks) {
-        let frequency = ADC::clock(&clocks).unwrap_or(clocks.sysclk());
+        let frequency = ADC::clock(&clocks).unwrap_or_else(|| clocks.sysclk());
         let cpu_cycles = cycles * clocks.sysclk().0 / frequency.0;
         asm::delay(cpu_cycles);
     }
@@ -417,7 +417,7 @@ where
         self.adc.cr.modify(|_, w| w.adstart().start());
         while self.adc.isr.read().eos().is_not_complete() {}
         self.adc.isr.modify(|_, w| w.eos().clear());
-        return self.adc.dr.read().rdata().bits();
+        self.adc.dr.read().rdata().bits()
     }
 
     /// This should only be invoked with the defined channels for the particular
@@ -478,7 +478,7 @@ where
     fn read(&mut self, _pin: &mut Pin) -> nb::Result<Word, Self::Error> {
         // TODO: Convert back to previous mode after use.
         let res = self.convert_one(Pin::channel());
-        return Ok(res.into());
+        Ok(res.into())
     }
 }