[PATCH] libertas: honor specific channel requests during association

Previously if a fixed channel was specified along with an SSID,
the channel request would be ignored during the association
process.  Instead, when searching for an adhoc or infrastructure
network to join, allow filtering results based on channel so
that the driver doesn't pick a BSS on a different channel than
requested.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>