HAL_ChibiOS: fixed delay for OneShot125 channels

we were delaying output for OneShot125 by 8x as much as we need to,
which reduced our max loop rate

libraries/AP_HAL_ChibiOS/RCOutput.cpp

@@ -387,7 +387,9 @@ void RCOutput::push_local(void)
                 } else if (group.current_mode == MODE_PWM_ONESHOT125) {
                     // this gives us a width in 125 ns increments, giving 1000 steps over the 125 to 250 range
                     uint32_t width = ((group.pwm_cfg.frequency/1000000U) * period_us) / 8U;
-                    pwmEnableChannel(group.pwm_drv, j, width);                    
+                    pwmEnableChannel(group.pwm_drv, j, width);
+                    // scale the period down so we don't delay for longer than we need to
+                    period_us /= 8;
                 } 
                 else if (group.current_mode < MODE_PWM_DSHOT150) {
                     uint32_t width = (group.pwm_cfg.frequency/1000000U) * period_us;