drm/i915: Add debug messages for pipe enable/disable

Currently we don't have any real indication when a pipe gets
enabled/disabled. Add some.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -2110,6 +2110,8 @@ static void intel_enable_pipe(struct intel_crtc *crtc)
 	int reg;
 	u32 val;
 
+	DRM_DEBUG_KMS("enabling pipe %c\n", pipe_name(pipe));
+
 	assert_planes_disabled(dev_priv, pipe);
 	assert_cursor_disabled(dev_priv, pipe);
 	assert_sprites_disabled(dev_priv, pipe);
@@ -2169,6 +2171,8 @@ static void intel_disable_pipe(struct intel_crtc *crtc)
 	int reg;
 	u32 val;
 
+	DRM_DEBUG_KMS("disabling pipe %c\n", pipe_name(pipe));
+
 	/*
 	 * Make sure planes won't keep trying to pump pixels to us,
 	 * or we might hang the display.