drm/amd/display: Remove duplicate include

Remove duplicate header which is included twice.
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c

@@ -35,7 +35,6 @@
 #include "dcn30_dpp.h"
 #include "dcn10/dcn10_cm_common.h"
 #include "dcn30_cm_common.h"
-#include "clk_mgr.h"
 #include "reg_helper.h"
 #include "abm.h"
 #include "clk_mgr.h"