kernel: move linux, part-probe dt parsing in generic code

kernel: move linux, part-probe dt parsing in generic code

The "linux,part-probe" dts parsing is a pretty neat generic feature.
It has been posted to kernel.org and could easily be reused by all
targets.

This change moves the patch to the 3.18 and 4.1 generic folders, and
makes the feature available to all platforms who may want to use it.

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46654 3c298f89-4303-0410-b956-a3cf2f4a3e73