i2c: Add Microchip PolarFire SoC I2C driver

Add I2C driver code for the Microchip PolarFire SoC.
This driver supports I2C data transfer and probe for I2C
slave addresses.

Signed-off-by: Padmarao Begari <padmarao.begari@microchip.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>