Add HiSilicon I2C controller driver for the Kunpeng SoC. It provides
the access to the i2c busses, which connects to the eeprom, rtc, etc.

The driver works with IRQ mode, and supports basic I2C features and 10bit
address. The DMA is not supported.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>