AA: ramips: add DIR-615 D userspace support

AA: ramips: add DIR-615 D userspace support

Backport of r34331.

Commit 7c8edac25f23c4fc14239fdc293caa1317649944 introduced new machine and
Makefile changes to build images for this target. However, without the userspace
bits a ramips machine can't use wifi as the necessary "eeprom" data is to be
extracted by a hotplug script; also, sysupgrade support and default led
configuration are missing.

An IRC user reported these changes allowed him to use wifi on his hardware.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
SVN-Revision: 34375