MAINTAINERS: ARM: EXYNOS: Add Krzysztof Kozlowski as co-maintainer

Add Krzysztof Kozlowski as a co-maintainer of Samsung Exynos ARM
architecture to review the patches. Patches will go as usual - picked up
by Kukjin Kim.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Kukjin Kim <kgene@kernel.org>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Acked-by: Tobias Jakobi <liquid.acid@gmx.net>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>