hamradio: baycom: remove useless link in Kconfig

The Kconfig help text for baycom drivers suggests that more information
on the hardware can be found at <https://www.baycom.de

>. The website now
includes no information on their ham radio products other than a mention
that they were once produced by the company, saying:
"The amateur radio equipment is now no longer part and business of BayCom GmbH"

As there is no information relavent to the baycom driver on the site,
remove the link.

Signed-off-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>