MAINTAINERS: Add Patchwork URL to Samsung Exynos entry

I use Patchwork for handling incoming patches. Put its address here so
submitters could know what is in the queue.

Signed-off-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: Javier Martinez Canillas <[email protected]>
Acked-by: Kukjin Kim <[email protected]>
1 file changed