drm/amdgpu: vcn_v2_5_mc_resume_dpg_mode() can be static

Fixes: c422a628925d ("drm/amdgpu: rename macro for VCN2.0 2.5 and 3.0")
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>