video/hdmi: Rename HDMI_IDENTIFIER to HDMI_IEEE_OUI

HDMI_IDENTIFIER was felt too generic, rename it to what it is, the IEEE
OUI corresponding to HDMI Licensing, LLC.

http://standards.ieee.org/develop/regauth/oui/oui.txt

Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>