ipq806x: Add ADM support

These are cherry-picked & backported from LKML:
*https://lkml.org/lkml/2015/3/17/19



They are enabled on both 3.18 and 4.1 kernel. Patches 150 to 154 are
applying changes merged since 3.18; they enable mechanisms used by the
ADM driver.

ADM engine is used by the NAND controller, so it is necessary to
bring-up NAND flash support.

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46567 3c298f89-4303-0410-b956-a3cf2f4a3e73