[PATCH] hostap: Add support for WE-19

This patch adds support for WE-19 to the HostAP driver. One of
the major change is the use of an explicit flag to tell if iwstat is
in dBm or not.

Signed-off-by: Jouni Malinen <jkmaline@cc.hut.fi>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>