drm/radeon/kms: don't use bios dividers for lvds on r4xx

R4xx cards don't have lvds pll dividers since they use atom.

should fix rh bug 541562
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_legacy_crtc.c

@@ -796,6 +796,7 @@ static void radeon_set_pll(struct drm_crtc *crtc, struct drm_display_mode *mode)
 			if (encoder->encoder_type != DRM_MODE_ENCODER_DAC)
 				pll_flags |= RADEON_PLL_NO_ODD_POST_DIV;
 			if (encoder->encoder_type == DRM_MODE_ENCODER_LVDS) {
+				if (!rdev->is_atom_bios) {
 					struct radeon_encoder *radeon_encoder = to_radeon_encoder(encoder);
 					struct radeon_encoder_lvds *lvds = (struct radeon_encoder_lvds *)radeon_encoder->enc_priv;
 					if (lvds) {
@@ -811,6 +812,7 @@ static void radeon_set_pll(struct drm_crtc *crtc, struct drm_display_mode *mode)
 				}
 			}
 		}
+	}
 
 	DRM_DEBUG("\n");