libcrc: make update_crc_econet work like crc_econet
libcrc: make update_crc_econet work like crc_econet

google/myelin-acorn-electron-hardware,google/myelin-acorn-electron-hardware,google/myelin-acorn-electron-hardware,google/myelin-acorn-electron-hardware,google/myelin-acorn-electron-hardware,google/myelin-acorn-electron-hardware