Revert "drm/radeon: Provide ddc symlink in connector sysfs directory"

This reverts commit bed7a218.

It causes the following build error:
../drm/radeon/radeon_connectors.c: In function 'radeon_add_legacy_connector':
../drm/radeon/radeon_connectors.c:2433:5: error: 'ddc' undeclared (first use in this function)
     ddc = &radeon_connector->ddc_bus->adapter;
     ^~~
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190801115313.22562-1-narmstrong@baylibre.com