When we add a standard timing mode in UMS, we will first check whether it can
be found in default mode table. If it can't be found, then we will use cvt/gtf
to add the standard timing mode.
Add the default mode table so that we can check whether the given mode
can be found in the default mode table as what we have done in UMS mode.

If the status of one output device is connected but there is no EDID, it will
have no correct mode. In such case we can add some default modes for it. Of
course we only add the modes in the default modes list that visible part is not
greater than 1024x768.

The default mode is autogenerated from the DMT spec. And it is copied from
xserver/hw/xfree86/modes/xf86EdidModes.c. But the mode with reduced blank
feature is removed.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>