ar71xx: add kernel support for GL-Inet V1 boards/routers

ar71xx: add kernel support for GL-Inet V1 boards/routers

The GL-Connect GL.iNet v1 router is basically a TP-Link TL-WR703N with
more DRAM/Flash, 2x Ethernet ports and console/GPIO header in the same
small form-factor:
<http://www.gl-inet.com/w/?lang=en>

Moreover, the manufacturer is promoting the OpenWrt usage to replace
the original firmware and proposing patches against both AA and trunk:
<http://www.gl-inet.com/w/?p=398&lang=en>

This is a clean up of the original manufacturer GPLv2 patch by alzhao,
proposed to the list by Mark Janssen.

Signed-off-by: Michel Stempin <michel.stempin@wanadoo.fr>
Signed-off-by: Mark Janssen <mark@sig-io.nl>
Signed-off-by: alzhao <alzhao@gmail.com>
Patchwork: http://patchwork.openwrt.org/patch/5273/
[juhosg:
  - remove user-space and image generation support, will be included
    from other patches,
  - fix coding style and drop superfluous comment in mach-gl-inet.c,
  - rename and refresh kernel patch,
  - adjust subject]
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41618 3c298f89-4303-0410-b956-a3cf2f4a3e73