bus: arm-ccn: Check memory allocation failure

Check memory allocation failures and return -ENOMEM in such cases

This avoids a potential NULL pointer dereference.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org # 3.17+
Signed-off-by: Pawel Moll <pawel.moll@arm.com>