drm/i915: Add CD and pixel clock information

This patch adds information of current and maximum CD clock
frequency and pixel clock frequency information on 'i915_debugfs.c'.

v2:
- combined seperate patches for current CD clock, maximum CD clock
  and maximum pixel clock
- space added between the frequency value and the unit
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1309,6 +1309,10 @@ static int i915_frequency_info(struct seq_file *m, void *unused)
 		seq_puts(m, "no P-state info available\n");
 	}
 
+	seq_printf(m, "Current CD clock frequency: %d kHz\n", dev_priv->cdclk_freq);
+	seq_printf(m, "Max CD clock frequency: %d kHz\n", dev_priv->max_cdclk_freq);
+	seq_printf(m, "Max pixel clock frequency: %d kHz\n", dev_priv->max_dotclk_freq);
+
 out:
 	intel_runtime_pm_put(dev_priv);
 	return ret;