drm/amdgpu: Remove unneeded semicolon in amdgpu_ras.c

Fixes coccicheck warning:

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:318:2-3: Unneeded semicolon

Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: zhengbin <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c

···
 	default:
 		ret = -EINVAL;
 		break;
-	};
+	}
 
 	if (ret)
 		return -EINVAL;