[package] uboot-imx6: alphabetize wandboard variants

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38203 3c298f89-4303-0410-b956-a3cf2f4a3e73
[package] uboot-imx6: add support for Nitrogen6x boards

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38204 3c298f89-4303-0410-b956-a3cf2f4a3e73