drm/i915: enable 30bpp for DP outputs

We always limited the link bw calculations to 24bpp. Tested with
my shiny new high-bpc screen, seems to work as advertised.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=65280Tested-by: Nshui yangwei <yangweix.shui@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -704,7 +704,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 
 	/* Walk through all bpp values. Luckily they're all nicely spaced with 2
 	 * bpc in between. */
-	bpp = min_t(int, 8*3, pipe_config->pipe_bpp);
+	bpp = pipe_config->pipe_bpp;
 	if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp)
 		bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);