amd8111e big-endian fix

amd8111e_calc_coalesce() ends up with insane values of tx_data_rate since
->tx_bytes increments missing conversion from little- to host-endian

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>