drm/i915: Use HPLLVCO_MOBILE for all PNVs

To allow unsetting .is_mobile for the desktop variant
of PNV fix up the cdclk code to select the mobile HPLLVCO register
for both PNV variants.

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190318165633.28924-5-ville.syrjala@linux.intel.com


Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>