The nvram_get function was never in the mainline kernel, it only existed in
an external OpenWrt patch. Use nvram_getenv function, which is in mainline
and use an include instead of an extra function declaration. et0macaddr
contains the mac address in text from like 00:11:22:33:44:55. We have to
parse it before adding it into macaddr.
nvram_parse_macaddr will be merged into asm/mach-bcm47xx/nvram.h through
the MIPS git tree and will be available soon. It will not build now without
nvram_parse_macaddr, but it hasn't before either.