package/tvheadend: bump version

package/tvheadend: bump version

It seems github now sometimes provides slightly changed tarballs which
produce a different sha256 hash than before, this is the case for
tvheadend. Instead of fixing the hash lets bump to current HEAD and
hope that the new hash will be valid for a longer period of time ;)

Fixes
http://autobuild.buildroot.net/results/59a/59ad7940dcd498cd0aaec26c8497b21e64379a6f/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>