package/kodi-pvr-zattoo: fix json dependency

package/kodi-pvr-zattoo: fix json dependency

Package depends on rapidjson, not rapidxml:
https://github.com/rbuehlma/pvr.zattoo/blob/Leia/CMakeLists.txt#L10

The bug was previously not noticed because kodi depends on rapidjson
https://github.com/xbmc/xbmc/blob/Leia/CMakeLists.txt#L133
and kodi-platform depends on kodi
https://github.com/xbmc/kodi-platform/blob/master/CMakeLists.txt#L8

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