[PATCH] radeonfb_old: Fix broken link

The link for ATI's product page in drivers/video/Kconfig for FB_RADEON is
broken.  Replace with a product comparison page.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>