MAINTAINERS: change email of TI WiLink drivers' maintainer

Soon the coelho@ti.com email will not be valid anymore, so change it
to my private one.

Cc: Luciano Coelho <luca@coelho.fi>
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>