Update maintainer for EHEA driver.

Since Thadeu left IBM, EHEA has gone mostly unmaintained, since his email
address doesn't work anymore.  I'm stepping up to help maintain this
driver upstream.

I'm adding Thadeu's personal e-mail address in Cc, hoping that we can
get his ack.

CC: Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br>
Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br>
Signed-off-by: David S. Miller <davem@davemloft.net>