I2C eeprom example.

This example project uses the EFM32 CMSIS and emlib including DK BSP
(board support package) and demonstrates the use of the I2C bus
accessing the EEPROM on the DK.

The first 3 bytes of the EEPROM is displayed on the TFT screen (this
will normally be FFFFFF first time.) Since stored in EEPROM, the data
survives resets and power cycles.

The following usage is possible:

- Joystick up/down will increment/decrement the first byte (Byte0) in
  the EEPROM. Byte1 is then set to Byte0+1, and Byte2 is set to Byte1+1.
- Press SW4 button to reset 3 first bytes to 0xFF.

Board:  Silicon Labs EFM32WG-DK3850 Development Kit
Device: EFM32WG990F256
