First I2C implementation

Initial I2C HAL implementation.
Only the I2cMaster was tested so far, I2cSlave will be tested next.

Master side was tested with a temerature sensor example application
in the vorago-reb1 crate

examples/spi.rs

@@ -12,7 +12,7 @@ use va108xx_hal::{
     gpio::{PinsA, PinsB},
     pac::{self, SPIA, SPIB},
     prelude::*,
-    spi::{self, NoneT, Spi, SpiBase, TransferConfig},
+    spi::{self, Spi, SpiBase, TransferConfig},
     timer::CountDownTimer,
 };
 

examples/timer-ticks.rs

@@ -29,7 +29,7 @@ fn main() -> ! {
     let mut dp = pac::Peripherals::take().unwrap();
     let mut last_ms = 0;
     rprintln!("-- Vorago system ticks using timers --");
-    set_sys_clock(50.mhz().into());
+    set_sys_clock(50.mhz());
     let lib_type = LibType::Hal;
     match lib_type {
         LibType::Pac => {