Currently SDVO TV only support NTSC-M format. In this patch
we introduce PAL and SECAM formats available and create seting-format
property at init time. When user dynamically chose preferred
format by xrandr command, it will refine all modelines
provided by SDVO device, then instruct SDVO device to execute.
At the same time the property is added for SDVO-TV so that the SDVO-TV mode can be changed
by using xrandr.

https://bugs.freedesktop.org/show_bug.cgi?id=22891Signed-off-by: Ma Ling <ling.ma@intel.com>
review-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>