i2c: qcom-cci: Remove unused struct member cci_clk_rate

The removal of the supply clock rate check implies a need to remove
some unnecessary left-over data from the driver as well.

Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>