drm: Remove duplicate drm_mode_cea_vic()

The same function had already been merged with a different name. Remove
the duplicate one but reuse some of its kerneldoc fragments for the
existing implementation.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>