drm/i915/ehl: Update voltage level checks

drm/i915/ehl: Update voltage level checks

The bspec was recently updated with new cdclk -> voltage level tables to
accommodate the new 324/326.4 cdclk values.

Bspec: 21809
Fixes: db38392a0e24 ("drm/i915/ehl: Add voltage level requirement table")
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Cc: Bob Paauwe <bob.j.paauwe@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191118164412.26216-1-matthew.d.roper@intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>