drm/radeon/kms: remove lvds quirks

- no longer needed with the latest new pll algo fixes.
- also don't use lcd pll limits.  They don't seem
to work well for all systems.  If we have a case where
they are useful, we can set the flag for that case.

fixes fdo bug 27083

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>