MIPS: Malta: Make use of generic CM support

Remove the Malta-specific CM probe code and instead make use of the
newly added generic CM code.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6364/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>