radeon/kms: fix dp displayport mode validation

Check if there is a big enough dp clock & enough dp lane to
drive the video mode provided.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-By: Alex Deucher <alexdeucher@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/radeon/atombios_dp.c

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 4e7778d..695de9a 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -187,9 +187,9 @@
 int dp_mode_valid(u8 dpcd[DP_DPCD_SIZE], int mode_clock)
 {
 	int lanes = dp_lanes_for_mode_clock(dpcd, mode_clock);
-	int bw = dp_lanes_for_mode_clock(dpcd, mode_clock);
+	int dp_clock = dp_link_clock_for_mode_clock(dpcd, mode_clock);
 
-	if ((lanes == 0) || (bw == 0))
+	if ((lanes == 0) || (dp_clock == 0))
 		return MODE_CLOCK_HIGH;
 
 	return MODE_OK;