AP_Notify: avoid suspend_timer_procs() by using atomic updates in ToshibaLED_PX4
AP_InertialSensor: use lockless structures in MPU9250 driver

this avoids suspending timers when transferring data between main
thread and SPI read thread
HAL_Linux: use a semaphore in suspend_timer_procs()

this is the start of multi-core aware code
Copter: show firmware version on param fetch

fixes pull #1320

thanks Arthur!
Rover: show firmware version on param list
Rover: remove unused variable