arm64: dts: exynos: gs101: update USI UART to use peric0 clocks

arm64: dts: exynos: gs101: update USI UART to use peric0 clocks

Get rid of the dummy clock and start using the cmu_peric0 clocks
for the usi_uart and serial_0 nodes.

Tested the serial at 115200, 1000000 and 3000000 baudrates,
everthing went fine.

Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/r/20240119111132.1290455-7-tudor.ambarus@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>