[POWERPC] mpc5200: merge defconfigs for all mpc5200 boards

There is no reason to have separate defconfigs for each mpc5200 board.
Instead, here is a common defconfig that can be used for all supported
platforms.

Merging the defconfigs means there are fewer configuration to test when
compile testing all of arch/powerpc and should make support easier.

Supported boards:
	Lite5200(b), Efika, TQM5200, CM5200, MotionPro
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>