MAINTAINERS: add dri-devel&linaro-mm for Android ION

Most of the other cross-driver gfx infrastructure (dma_buf, dma_fence)
also gets cross posted to all the relevant gfx/memory lists. Doing the
same for ION means people won't miss relevant patches.

Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Acked-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -905,6 +905,8 @@ ANDROID ION DRIVER
 M:	Laura Abbott <labbott@redhat.com>
 M:	Sumit Semwal <sumit.semwal@linaro.org>
 L:	devel@driverdev.osuosl.org
+L:	dri-devel@lists.freedesktop.org
+L:	linaro-mm-sig@lists.linaro.org (moderated for non-subscribers)
 S:	Supported
 F:	drivers/staging/android/ion
 F:	drivers/staging/android/uapi/ion.h