[POWERPC] CPM2: Reset the CPM when early debugging is not enabled.

Similarly to what is done for PQ1-based platforms, this patch resets the
PQ2 Communication Processor Module in cpm2_reset() when early debugging is
not enabled. This helps avoiding conflicts when the boot loader configured
the CPM in an unexpected way.

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>