drm/i915: Add 324mhz and 326.4mhz cdclks for gen11+

The bspec was recently updated with these new cdclk values for ICL, EHL,
and TGL.

Bspec: 20598
Bspec: 49201
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190826225540.11987-3-matthew.d.roper@intel.com