MAINTAINERS: Change Krzysztof Kozlowski's email address

Switch Krzysztof Kozlowski's to @kernel.org account.

Link: https://lore.kernel.org/r/20240329174823.74918-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>