arm64: dts: exynos: convert serial_0 to USI on ExynosAutov9

arm64: dts: exynos: convert serial_0 to USI on ExynosAutov9

According to USI v2 driver change[1], serial_0 node should be converted to
use the USI node hierarchy. syscon_peric0 will be used as a syscon node
to control the USI00_USI_SW_CONF register.
This also changes the serial node name from uart@ to serial@.

[1]: https://lore.kernel.org/linux-samsung-soc/20211204195757.8600-2-semen.protsenko@linaro.org/

Cc: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20211208091853.8557-1-chanho61.park@samsung.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>