radeonfb: revert "Fix radeon DDC regression"

The bug was in fb_ddc and was fixed by commit
b64d7082 (fb_ddc: fix DDC lines quirk) so
the workaround in radeonfb can be removed now.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>