MAINTAINERS: update entry for Yealink driver

Remove reference to no longer working usbb2k-api-dev@nongnu.org
mailing list.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

MAINTAINERS

@@ -24805,7 +24805,6 @@ F:	tools/net/ynl/
 
 YEALINK PHONE DRIVER
 M:	Henk Vergonet <Henk.Vergonet@gmail.com>
-L:	usbb2k-api-dev@nongnu.org
 S:	Maintained
 F:	Documentation/input/devices/yealink.rst
 F:	drivers/input/misc/yealink.*