drm/sti: remove duplicate object names

When merging 2 drivers common object files were not deduplicated.

Fixes: dcec16e ("drm/sti: Build monolithic driver")
Cc: stable@kernel.org
Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/1920148.tdWV9SEqCh@devpool47.emlix.com
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>

Author: DerDakon

drivers/gpu/drm/sti/Makefile

@@ -7,8 +7,6 @@ sti-drm-y := \
 	sti_compositor.o \
 	sti_crtc.o \
 	sti_plane.o \
-	sti_crtc.o \
-	sti_plane.o \
 	sti_hdmi.o \
 	sti_hdmi_tx3g4c28phy.o \
 	sti_dvo.o \