[bsp] fix the return of the function(drv_pwm_control) in stm32 drv_pwm

bsp/stm32/libraries/HAL_Drivers/drv_pwm.c

@@ -396,7 +396,7 @@ static rt_err_t drv_pwm_control(struct rt_device_pwm *device, int cmd, void *arg
     case PWM_CMD_GET:
         return drv_pwm_get(htim, configuration);
     default:
-        return RT_EINVAL;
+        return -RT_EINVAL;
     }
 }