drm/amdgpu/display: remove duplicate include header in files

opp.h is included more than once.
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link.c

@@ -46,7 +46,6 @@
 #include "dpcd_defs.h"
 #include "dmcu.h"
 #include "dsc.h"
-#include "opp.h"
 #include "hw/clk_mgr.h"
 #include "dce/dmub_psr.h"
 #include "dmub/dmub_srv.h"