Partially revert 5e3a602def. Unfortunately the ethaddr value in U-Boot
environment is enclosed in double quotes which makes it longer than
ETH_ALEN, thus nvmem returns EINVAL. Switch back to handling the MAC
addresses in user space.
Fixes: 5e3a602def ("ath79: sitecom,wlrx100: use nvmem")
Reviewed-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Tomasz Maciej Nowak <tmn505@gmail.com>