Update linux-sun7i to 3.4.79 and add support for cubietruck

This is a reworked version of a previous PR to update linux-sun7i to add cubietruck support.

This PR is based on the PKGBUILD and config from the current version of linux-sun7i.
I have been running this version on my cubietruck for the past week and it has been very stable for me. I also asked users in the forum to test it out on other sun7i devices: http://archlinuxarm.org/forum/viewtopic.php?f=33&t=6413&start=60

So far one other user, fcarolo, has tested it on the cubieboard2 and cubietruck and confirmed that it works on both.

Note that this kernel also includes a patched `bcmdhd` driver which makes the onboard wifi work on the cubietruck.