kernel: update 3.18 to 3.18.14

Changelogs:

* https://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.18.12
* https://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.18.13
* https://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.18.14



Build tested on brcm63xx and ipq806x, runtested on brcm63xx.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45711 3c298f89-4303-0410-b956-a3cf2f4a3e73