drm/amdgpu: remove duplicated include from gfx_v9_0.c

Remove duplicated include.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c

@@ -40,7 +40,6 @@
 #include "vega10_enum.h"
 #include "hdp/hdp_4_0_offset.h"
 
-#include "soc15.h"
 #include "soc15_common.h"
 #include "clearstate_gfx9.h"
 #include "v9_structs.h"