drm/i915: Dump ddi_pll_sel in hex instead of decimal on HSW/BDW

On HSW/BDW ddi_pll_sel is the actual register value. Let's dump
it in hex so that people migth actually understand what it says.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1455738073-14502-2-git-send-email-ville.syrjala@linux.intel.com


Reviewed-by: Imre Deak <imre.deak@intel.com>