drm/amd/pm: Prevent division by zero

The user can set any speed value.
If speed is greater than UINT_MAX/8, division by zero is possible.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: c52dcf4 ("drm/amd/pp: Avoid divide-by-zero in fan_ctrl_set_fan_speed_rpm")
Signed-off-by: Denis Arefev <arefev@swemel.ru>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

Author: Denis Arefev

drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_thermal.c

@@ -307,10 +307,10 @@ int vega10_fan_ctrl_set_fan_speed_rpm(struct pp_hwmgr *hwmgr, uint32_t speed)
 	int result = 0;
 
 	if (hwmgr->thermal_controller.fanInfo.bNoFan ||
-	    speed == 0 ||
+	    (!speed || speed > UINT_MAX/8) ||
 	    (speed < hwmgr->thermal_controller.fanInfo.ulMinRPM) ||
 	    (speed > hwmgr->thermal_controller.fanInfo.ulMaxRPM))
-		return -1;
+		return -EINVAL;
 
 	if (PP_CAP(PHM_PlatformCaps_MicrocodeFanControl))
 		result = vega10_fan_ctrl_stop_smc_fan_control(hwmgr);