km83xx: add common support for km8309 boards

Add support for Keymile boards based on mpc8309
(it would be only kmvect1 for now)

Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
[#elseif -> #if to allow kmcoge5ne and kmeter1 to build successfully]
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>