Fix incorrect data rate setting for x1 data bit rate factor

Bug fix: incorrect data rate setting for x1 data bit rate factor and Data Bit Rate Switch (thanks to Pablo Ortega). Before this release:

• CANFD sent frames always had the BSR bit clear, even if frame type is CANFDMessage::CANFD_WITH_BIT_RATE_SWITCH;
• CANFD network frames with the BSR bit set were not received.

Added sample code for Adafruit Feather M0.