Revert "[DVB-T Scans] Scan both DVB-T/T2 when 'system' is not specified in terrestrial.xml. And, eDVBscan: add sanitycheck on m_ch_current. Requested by Abu Baniaz. Credit OpenPLi (pieterg, 24/7/2014)."

This reverts commit 1834e4f6f26a5e042dc3ef4cbed4f59fad033d45.