brcm80211: add mailing list address for brcm80211 drivers

Added the mailing list address brcm80211-dev-list@broadcom.com
which can be used to report issues and in bug reports.

Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>