MAINTAINERS: clock: include S3C and S5P in Samsung SoC clock entry

Cover the S3C and S5Pv210 clock controller binding headers by Samsung
SoC clock controller drivers maintainer entry.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20210825134251.220098-3-krzysztof.kozlowski@canonical.com
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>