Fixes coccicheck warning:

drivers/gpu/drm/amd/powerplay/hwmgr/vega12_hwmgr.c:502:5-11: Unneeded variable: "result". Return "0" on line 515
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>