drm/exynos: let drm handle edid allocations

There's no need to allocate edid twice and do a memcpy when drm helpers
exist to do just that. This patch cleans that interaction up, and
doesn't keep the edid hanging around in the connector.

v4:
- removed error check for drm_mode_connector_update_edid_property
which is expected to fail for Virtual Connectors like VIDI.
Thanks to Seung-Woo Kim.

v3:
- removed MAX_EDID as it is not used anymore.

v2:
- changed vidi_get_edid callback inside vidi driver.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>