MAINTAINERS: add drm/sti driver into drm-misc

drm/sti driver is now part of drm-misc as a small driver.
Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1491835958-30229-1-git-send-email-vincent.abriou@st.com

MAINTAINERS

@@ -4417,7 +4417,7 @@ DRM DRIVERS FOR STI
 M:	Benjamin Gaignard <benjamin.gaignard@linaro.org>
 M:	Vincent Abriou <vincent.abriou@st.com>
 L:	dri-devel@lists.freedesktop.org
-T:	git http://git.linaro.org/people/benjamin.gaignard/kernel.git
+T:	git git://anongit.freedesktop.org/drm/drm-misc
 S:	Maintained
 F:	drivers/gpu/drm/sti
 F:	Documentation/devicetree/bindings/display/st,stih4xx.txt