finally I made it!
long story short, after a few beers and a lot of thinking work I manage to get a clue from an error message
has a dependency on 'kmod-spi-bcm2708', which does not exist
then I modify ~/openwrt/package/kernel/enc28j60/Makefile the next line
DEPENDS:=+kmod-spi-bcm2708
for this one
DEPENDS:=+kmod-spi-bcm2835
then the eth1 apears and works nice!
thanks for the patch and the hint I will keep it on my book of tricks