drm/i915: Fix stale comment for intel_ddi_pll_select()

Since the run-time PM on DPMS series, this function has an outdated
comment. Refresh it a bit.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -709,10 +709,11 @@ intel_ddi_calculate_wrpll(int clock /* in Hz */,
 }
 
 /*
- * Tries to find a PLL for the CRTC. If it finds, it increases the refcount and
- * stores it in intel_crtc->ddi_pll_sel, so other mode sets won't be able to
- * steal the selected PLL. You need to call intel_ddi_pll_enable to actually
- * enable the PLL.
+ * Tries to find a *shared* PLL for the CRTC and store it in
+ * intel_crtc->ddi_pll_sel.
+ *
+ * For private DPLLs, compute_config() should do the selection for us. This
+ * function should be folded into compute_config() eventually.
  */
 bool intel_ddi_pll_select(struct intel_crtc *intel_crtc)
 {