MAINTAINERS: drop dri-devel list for i915

In practice, none of the i915 developers Cc dri-devel for strictly i915
specific patches. Make MAINTAINERS reflect reality, and reduce random
i915 specific noise on dri-devel.

Also, we have a fairly large crowd reading and responding on intel-gfx,
and we're pretty good at involving dri-devel when that is appropriate.

Cc: dri-devel@lists.freedesktop.org
Acked-by: NDaniel Vetter <daniel@ffwll.ch>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1477498292-9808-1-git-send-email-jani.nikula@intel.com

MAINTAINERS

@@ -4054,7 +4054,6 @@ INTEL DRM DRIVERS (excluding Poulsbo, Moorestown and derivative chipsets)
 M:	Daniel Vetter <daniel.vetter@intel.com>
 M:	Jani Nikula <jani.nikula@linux.intel.com>
 L:	intel-gfx@lists.freedesktop.org
-L:	dri-devel@lists.freedesktop.org
 W:	https://01.org/linuxgraphics/
 Q:	http://patchwork.freedesktop.org/project/intel-gfx/
 T:	git git://anongit.freedesktop.org/drm-intel