drm/amdgpu: Remove useless amdgpu_display_freesync_ioctl() declaration

Signed-off-by: Leslie Shi <Yuliang.Shi@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_display.h

@@ -35,8 +35,6 @@
 #define amdgpu_display_add_encoder(adev, e, s, c) (adev)->mode_info.funcs->add_encoder((adev), (e), (s), (c))
 #define amdgpu_display_add_connector(adev, ci, sd, ct, ib, coi, h, r) (adev)->mode_info.funcs->add_connector((adev), (ci), (sd), (ct), (ib), (coi), (h), (r))
 
-int amdgpu_display_freesync_ioctl(struct drm_device *dev, void *data,
-				  struct drm_file *filp);
 void amdgpu_display_update_priority(struct amdgpu_device *adev);
 uint32_t amdgpu_display_supported_domains(struct amdgpu_device *adev,
 					  uint64_t bo_flags);