MAINTAINERS: add myself as co-maintainer of the iwlwifi driver

I'm starting to take a more active role in the iwlwifi driver
maintainership.

Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: NLuca Coelho <luciano.coelho@intel.com>

MAINTAINERS

@@ -5831,6 +5831,7 @@ F:	drivers/net/wireless/intel/iwlegacy/
 INTEL WIRELESS WIFI LINK (iwlwifi)
 M:	Johannes Berg <johannes.berg@intel.com>
 M:	Emmanuel Grumbach <emmanuel.grumbach@intel.com>
+M:	Luca Coelho <luciano.coelho@intel.com>
 M:	Intel Linux Wireless <linuxwifi@intel.com>
 L:	linux-wireless@vger.kernel.org
 W:	http://intellinuxwireless.org