i2c: mvtwsi: disable i2c slave also on Armada 8k

The hidden I2C slave is also present on the Armada 8k AP806. Testing
shows that this I2C slave causes the same issues as Armada 38x.
Disabling that I2C slave fixes all these issues.

I2C blocks on the Armada 8k CP110 are not affected.

Extend the I2C slave disable to Armada 8k as well.

Cc: Stefan Roese <sr@denx.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>