drm/i915/adl_p: Enable/disable loadgen sharing

Disable loadgen sharing for DP link rate 1.62 GHz and HDMI 5.94 GHz.
For all other modes, we can enable loadgen sharing feature.

BSpec: 55359

Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Clinton Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210514153711.2359617-13-matthew.d.roper@intel.com