i2c: rk3x: add Kconfig dependency on COMMON_CLK

Now that we are using the clk notifier framework we get compile errors
without COMMON_CLK. But the driver fails to probe without COMMON_CLK
anyways, so just add that as a Kconfig dependency.

Signed-off-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>