package/bcg729: update the upstream URL in Config.in

Update the upstream URL in the help text in Config.in. This
addresses the 'Invalid(404)' URL status in the package stats
web page output.

Signed-off-by: Mark Corbin <mark@dibsco.co.uk>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/bcg729/Config.in

@@ -4,4 +4,4 @@ config BR2_PACKAGE_BCG729
 	  Bcg729 is an opensource implementation of both encoder and
 	  decoder of the ITU G729 Annex A/B speech codec.
 
-	  http://www.linphone.org/technical-corner/bcg729/overview
+	  https://www.linphone.org/technical-corner/bcg729