tty: serial: samsung: Add Exynos850 SoC data

Add serial driver data for Exynos850 SoC. This driver data is basically
reusing EXYNOS_COMMON_SERIAL_DRV_DATA, which is common for all Exynos
chips, but also enables USI init, which was added in previous commit:
"tty: serial: samsung: Init USI to keep clocks running".

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20210811114827.27322-7-semen.protsenko@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>