Enable the pca9555 chip on mec172xevb to test the I2C function
1. Add tests/boards/mec172xevb_assy6906/i2c_api
2. The HW connections are described in README.txt
3. Use I2C01 to connect the PCA9555, as I2C00 is for UART2
Signed-off-by: Hu Zhenyu <zhenyu.hu@intel.com>
