drm/i915/skl: Remove spurious warn in get_ddi_pll()

When reading out a DDI config that uses a PLL that is not part of the
shared_dpll scheme (DPLL0), it's totally normal to end up in the
default: case of that switch.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -8029,8 +8029,6 @@ static void skylake_get_ddi_pll(struct drm_i915_private *dev_priv,
 	case SKL_DPLL3:
 		pipe_config->shared_dpll = DPLL_ID_SKL_DPLL3;
 		break;
-	default:
-		WARN(1, "Unknown DPLL programmed\n");
 	}
 }