u-boot-denx: add v2013.10

zImage is now the default

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
ti33xx.inc: make zImage the default image format to match u-boot v2013.10

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
linux-mainline 3.8: soft assign image time, switch to zImage

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>