Switch I2C2 to i2c-gpio driver

- Mediatek's hardware block driver doesn't support SMBus Read Block,
which is required by our A71CH device.
- Switch to the i2c-gpio bitbang driver to gain proper support for read
block.

Change-Id: Ie9a53331cae6a84a0ed2bacef583ae9ce6220725
1 file changed