drm/i915/ehl: Ungate DDIC and DDID

Specification states that DDI_CLK_SEL needs to be mapped to MG clock
even if MG do not exist on EHL, this will ungate those DDIs.

BSpec: 20845
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Tested-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190730175121.16413-1-jose.souza@intel.com