MAINTAINERS: change NX/VMX maintainers

Add Breno and Nayna as NX/VMX crypto driver maintainers. Also change my
email address to my personal account and remove Leonidas since he's not
working with the driver anymore.

Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>