Sometimes we will get the incorrect display modeline when parsing the detailed
timing in EDID. For example:
   >hsync/vsync width is zero
   >sync is beyond the blank.

So add the basic check for the detailed timing in EDID to avoid the incorrect
display modeline.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>