package/tvheadend: Enable bundled build

host-python is needed to create a bundled version of the tvheadend binary which
includes all files used by the web UI.

Having host-python alone as dependency is not enough, we need to add
--enable-bundle to enable this functionality.

Also remove the now bundled webinterface files from /usr/share/tvheadend/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>