Setting PWM_DISARMED to 0 results in no PWM output to the ESC for the pusher motor.
Most ESCs start beeping endless in short intervals if they don't get a signal.
I remove changing this parameter which is 900 by default to always command the motor to stand still.
* added a parameter for enabled the smart battery
* start tel1 and tel2 at 921600 and max rate
* turned up the max tx rate on mavlink streams for telem1 and telem2
* turned off mavlink stream for tel1 in 4250_teal. This is connected to TX1 FTDI UART and has issues.
* moved check to 4250 board ID to start mpu9250s for Teal airframe into fmuv4 rc.board.