The TV detection logic is not reliable on the Cantiga platform.
Sometimes the TV will be misdetected as the following two cases:
- TV is misdetected on some laptops. e.g. There is no TV connector
port or no TV is attached. But the TV is shown as connected.
- TV connector type is misdetected. e.g. the component TV is
attached, but the TV is shown as S-video type.

According to the hardware requirement, the TV sense state bits of TV DAC
register should be cleared to zero on Cantiga platfrom.

https://bugzilla.kernel.org/show_bug.cgi?id=14792

Cc: Stable Team <stable@kernel.org>
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Tested-by: Santi <santi@agolina.net>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>