imx6q-sabrelite: use new features in u-boot, NOTE bootloader is now installed seperately see: http://eewiki.net/display/linuxonarm/i.MX6x+SABRE+Lite#i.MX6xSABRELite-Initialboot:UpgradeBootloader

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>