pandaboard: update for using uEnv and scr files as needed

updated build configuration etc

Signed-off-by: Nishanth Menon <nm@ti.com>
Build support for PandaBoard ES revision

Signed-off-by: Nishanth Menon <nm@ti.com>
configs: add support for bonelt

Signed-off-by: Nishanth Menon <nm@ti.com>
Merge branch 'master' into bone-devel
bonelt: switch to mmc boot

Signed-off-by: Nishanth Menon <nm@ti.com>