[PATCH] Restore channel setting after scan.

After a scan, we weren't switching back to the original channel if we
were associated with an AP. So NetworkManager's periodic scans would
disrupt connectivity until the ESSID was manually set again. Fix that.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>