scripts/patch-kernel script can't patch a tree, say, from 2.6.25 to
2.6.26.1, because of a wrong comparison in context of patching 2.6.x base.
 Fix it.

Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>