[POWERPC] fsldma: Use compatiable binding as spec

Documentation/powerpc/booting-without-of.txt specifies the
compatiables we should bind to for this driver (elo, eloplus).
Use these instead of the extremely specific 'mpc8540' and 'mpc8349'
compatiables.

Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>