Copter: faster baro calibration when arming

using update_calibration() instead of the full calibrate() cuts
1.5seconds of the arming time
HAL_PX4: be less verbose about disarmed PWM setup
HAL_PX4: more checking of IO results in eeprom driver
PX4: test MTD device on boot

full rwtest on FMUv2, read test on FMUv1
INS: shortened gyro calibration

Removed delays before calibration, reduced number of samples taken,
widened convergence criteria
Copter: Added GCS feedback for save_trim()

Trim save gives no feedback, so I've added a gcs_send_text() call to
print "Trim saved" so the user knows to re-center trims again