I was getting the most of information from here.
Thanks a lot.

I have build a archiv. After unpacking you must put the content into the openwrt-15.05 sourcecode.
And now you can build your own openwrt including the enc28j60 module.
(md5sum = 3d4dccbdcef5bd8f9f6311823e7324f9)

here the description what i have done:
The sourcecode for kerneldriver are in the mainline kernel source at this place:
I have copy them to ./package/kernel/enc28j60/src to make a openwrt module
There a small change in the code necessary, for this see the patch.
The other file which is changed and the reason why it is necessary to make a new build of openwrt,
is this file:
there are only a small change. For this you can see the ./target/linux/brcm2708/patches-3.18/1010-enc28j60-spidev.patch

(Last edited by Plonk34 on 19 Aug 2015, 14:03)