MAINTAINERS: soc: reference maintainer profile

Mention the SoC maintainer profile in P: entry.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230723131924.78190-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Arnd Bergmann <arnd@arndb.de>