qtdemux: fix wrong full_range offset when parsing colr box
use colr_data[18] >> 7 to get full range information, instead of colr_data[17] >> 7
following hex code is a colr box example, the offset of 0x80 is 18
00 00 00 13 63 6F 6C 72 6E 63 6C 78 00 01 00 01 00 00 80
Edited by HuQian