Designs the sequence header syntax to support various
profiles as decided in the AV1 codec WG:

Profile 0: 4:2:0 and 4:0:0 8/10-bit
Profile 1: 4:4:4 8/10-bit
Profile 2: 4:2:0/4:0:0/4:4:4 12-bit as well as 4:2:2 8/10/12-bit

Change-Id: Iea351698280e37d65847bf75a43c5bbeba8f7cf4