drm/radeon/kms/atom: fix typo in LVDS panel info parsing

Fixes LVDS issues on some laptops; notably laptops with
2048x1536 panels.

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

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -1174,7 +1174,7 @@ struct radeon_encoder_atom_dig *radeon_atombios_get_lvds_info(struct
 		lvds->native_mode.vtotal = lvds->native_mode.vdisplay +
 			le16_to_cpu(lvds_info->info.sLCDTiming.usVBlanking_Time);
 		lvds->native_mode.vsync_start = lvds->native_mode.vdisplay +
-			le16_to_cpu(lvds_info->info.sLCDTiming.usVSyncWidth);
+			le16_to_cpu(lvds_info->info.sLCDTiming.usVSyncOffset);
 		lvds->native_mode.vsync_end = lvds->native_mode.vsync_start +
 			le16_to_cpu(lvds_info->info.sLCDTiming.usVSyncWidth);
 		lvds->panel_pwr_delay =