[flashrom] PATCH: whitelist for ThinkPad T500 and R400

[Francis Rowe]

Dear flashrom community,

Attached is my patch adding a whitelist to flashrom, for these laptops:
* ThinkPad R400
* ThinkPad T500

Both laptops were added to coreboot recently, so it makes sense for
flashrom to have a whitelist.

Hope the community finds this useful.

Regards,
Francis Rowe.

PS: This was made on top of stefanct's git repository, pulled from his
github profile.