drm/i915/dg2: configure TRANS_DP2_CTL for DP 2.0

Set the DP 2.0 128b/132b channel encoding for UHBR rates.

v2: Fix UHBR port clock check, use intel_dp_is_uhbr()

Bspec: 54128
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c88b08d80a96d1229ae941b296590633be4d8711.1631191763.git.jani.nikula@intel.com