DISCO_F469NI: allow the use of CAN2 instance when CAN1 is not activated
DISCO_F469NI: allow the use of CAN2 instance when CAN1 is not activated

j-greffe/mbed-os,j-greffe/mbed-os,j-greffe/mbed-os,j-greffe/mbed-os,j-greffe/mbed-os,j-greffe/mbed-os