drm/amd/pm: Clean up errors in hardwaremanager.h

Fix the following errors reported by checkpatch:

ERROR: open brace '{' following struct go on the same line
Signed-off-by: Ran Sun <sunran001@208suo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/powerplay/inc/hardwaremanager.h

@@ -44,8 +44,7 @@ struct phm_fan_speed_info {
 };
 
 /* Automatic Power State Throttling */
-enum PHM_AutoThrottleSource
-{
+enum PHM_AutoThrottleSource {
     PHM_AutoThrottleSource_Thermal,
     PHM_AutoThrottleSource_External
 };