staging: r8821ae: Fix potential problem with rate control registration

The zero day testing facility reported a problem with duplicate
registration of the rate-control algorithm. Although not yet reported,
this driver needs the same fix.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>