drm/i915/ehl: Remove unsupported cd clocks

EHL do not support 648 and 652.8 MHz.

v2:
- Limiting maximum CD clock by max_cdclk_freq instead of remove it
from icl_calc_cdclk()(Ville and Jani)

BSpec: 20598
Cc: Clint Taylor <Clinton.A.Taylor@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190626014053.30541-2-jose.souza@intel.com