mpc83xx: Removed #ifdef CONFIG_MPC834X dependency on upmconfig function

This is done to allow other 83XX based platforms which also have UPM
(e.g. 8360) to configure and use their UPM in u-boot.

Signed-off-by: Richard Retanubun <RichardRetanubun@RuggedCom.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>