rtlwifi: Update beacon statistics for USB driver

commit 65b9cc97c6852fae19dc5c7745e9abc8dd380aad upstream.

The USB drivers were not updating the beacon statistics, which led to
false beacon loss indications.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>