drm/i915: access the PP_ON_DELAYS/PP_OFF_DELAYS regs only pre GEN5

These registers exist only before GEN5, so currently we may access
undefined registers on VLV/CHV and BXT. Apply the workaround only pre
GEN5.

Since the workaround is relevant only when LVDS is present, for clarity
apply it only if this is the case.

This triggered an unclaimed register access warning on BXT.

v2: (Ville)
- move the workaround to the LVDS init code
- print a debug note about the workaround

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_bios.c

@@ -1340,21 +1340,3 @@ intel_parse_bios(struct drm_device *dev)
 
 	return 0;
 }
-
-/* Ensure that vital registers have been initialised, even if the BIOS
- * is absent or just failing to do its job.
- */
-void intel_setup_bios(struct drm_device *dev)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-
-	 /* Set the Panel Power On/Off timings if uninitialized. */
-	if (!HAS_PCH_SPLIT(dev) &&
-	    I915_READ(PP_ON_DELAYS) == 0 && I915_READ(PP_OFF_DELAYS) == 0) {
-		/* Set T2 to 40ms and T5 to 200ms */
-		I915_WRITE(PP_ON_DELAYS, 0x019007d0);
-
-		/* Set T3 to 35ms and Tx to 200ms */
-		I915_WRITE(PP_OFF_DELAYS, 0x015e07d0);
-	}
-}