build scripts: fix 'make defconfig' damage

build scripts: fix 'make defconfig' damage

Looking at the target 'defconfig' in include/toplevel, it doesn't
directly reference $(HOME)/.openwrt/defconfig nor does it reference any
prerequisites using it as a target.

Therefore, building "defconfig" as a target uses the defaults in the
tree, but not the defaults that a user might have explicitly specified.

This patch fixes this regression from r36361.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
[florian: apply with the proper patch level, wrap at 80 columns]
Signed-off-by: Florian Fainelli <florian@openwrt.org>
SVN-Revision: 37883