drm/i915/dp: Write the source OUI for non-eDP sinks as well

At least the i-tec USB-C Nano 2x Display Docking Station (containing a
Synaptics MST branch device) requires the driver to update the source
OUI DPCD registers to expose its DSC capability. Accordingly update the
OUI for all sink types (besides eDP where this has been done already).

v2: Rebased on latest patch version.

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11776


Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241025160259.3088727-9-imre.deak@intel.com