The number of bits (binary 000 to 1000) in the previous
BIP-8 that didn't match the even parity check are inserted
by the transmitter. The receiver checks for this in the
M0/M1 byte of the frame. A non-zero value (legal range
is binary 0000 - 1000) indicates a line layer error in
the remote end. Any other value is treated as no error.
Count of Line Far End Bit Errors (FEBE) on this phy.