drm/tegra: Don't set a gamma table size

Tegra doesn't have any functions to set gamma tables, so this is
completely defunct.

Not nice to lie to userspace, so let's stop!

Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/dc.c

@@ -1722,7 +1722,6 @@ static int tegra_dc_init(struct host1x_client *client)
 	if (err < 0)
 		goto cleanup;
 
-	drm_mode_crtc_set_gamma_size(&dc->base, 256);
 	drm_crtc_helper_add(&dc->base, &tegra_crtc_helper_funcs);
 
 	/*