Add clock controller support for Peripheral Connectivity 0 and 1 blocks.
These provide clocks for USI, I2C and UART peripherals.
Some clocks need to be marked as critical to prevent system hang when
disabled.
Signed-off-by: Denzeel Oliva <wachiturroxd150@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>