Clean the following coccicheck warning:

./drivers/gpu/drm/amd/pm/legacy-dpm/si_dpm.c:7035:2-4: WARNING: possible
condition with no effect (if == else).
Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: NJiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>