drm/radeon/kms: use lcd pll limits when available

The bios has alternate pll output limits for LCD panels.
If available, use these for pll divider calculations.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
index 0c67669..a8cd637 100644
--- a/drivers/gpu/drm/radeon/atombios_crtc.c
+++ b/drivers/gpu/drm/radeon/atombios_crtc.c
@@ -525,6 +525,7 @@
 				if (encoder->encoder_type == DRM_MODE_ENCODER_LVDS) {
 					struct radeon_encoder_atom_dig *dig = radeon_encoder->enc_priv;
 					pll->algo = dig->pll_algo;
+					pll->flags |= RADEON_PLL_IS_LCD;
 				}
 			} else {
 				if (encoder->encoder_type != DRM_MODE_ENCODER_DAC)