[Xorg-driver-geode] Mode_valid function workaround method for geode

[Huang, FrankR]

	Julien, Adam, Matthew, Matt, thanks a lot for you to give me
suggestion and explanation in detail on my patch for *_mode_valid.
Always I appreciate any feedback from the community. We are all for good
code. I am also a coder and driver maintainer, so I hate wrong code too,
especially that will lead a bug.
	Thanks for Mitch's help, I know quite more on what you guys mean
in your mail, especially you are experienced coder on X.
	Actually, I understand what you mean about the "wrong code" on
my patch. After the change of the last return value from MODE_BAD to
MODE_OK, that will make the whole function return ONLY "MODE_OK" VALUE.