[ltp] Dropping thinkpad-acpi backport support for 2.6.20, 2.6.21

[Henrique de Moraes Holschuh]

On Sat, 09 Feb 2008, Henrique de Moraes Holschuh wrote:
> Therefore, I will be dropping 2.6.20 and 2.6.21 from further thinkpad-acpi
> releases.

I decided to do a few more to get some functionality in sync on all branches
since there are a lot of 2.6.20 downloads in sourceforge.net, but there
won't be many more 2.6.20/2.6.21 updates.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh