Update firmware.info.xml with 2foc ver 3.3.26

[MSECode]

This PR brings the following changes - As define for robotology/icub-firmware#466:

• PWM frequency reduced from 40 kHz to 20 kHz
• Improving of the management of errors conditions in the temperature reading:
  • as described in the documentation different negative temperatures are sent to the user for showing different error conditions
  • at each error in the TDB where we are loosing the correct configuration of the board we are calling its re-configuration
  • temperature sent over CAN towards the EMS in the moment the reading is done
  • reading is now at 100 ms
  • if motor stays in overtemperature for more than 10 consecutive seconds we are putting the joint in fault, otherwise we just send warnings
  • if we cannot read from the TDB for more than 10 consecutive seconds we are putting the joint in fault, otherwise we try to reconfigure the sensor
  • the overheating error is removed when the read temperature is just less than the given threshold
• introduced a methods (never called) for generating synthetic temperature data
• now the default value for the stator-rotor offset is not 0x0000 but is 0xFFFF

[valegagge]

LGTM

[valegagge]

cc @marcoaccame @ale-git