drm/i915/bios: fix off by one in parse_generic_dtd()

The "num_dtd" variable is the number of elements in the
generic_dtd->dtd[] array so the > needs to be >= to prevent reading one
element beyond the end of the array.

Fixes: 33ef6d4f ("drm/i915/vbt: Handle generic DTD block")
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191212091130.zf2g53njf5u24wk6@kili.mountain

drivers/gpu/drm/i915/display/intel_bios.c

@@ -340,7 +340,7 @@ parse_generic_dtd(struct drm_i915_private *dev_priv,
 
 	num_dtd = (get_blocksize(generic_dtd) -
 		   sizeof(struct bdb_generic_dtd)) / generic_dtd->gdtd_size;
-	if (dev_priv->vbt.panel_type > num_dtd) {
+	if (dev_priv->vbt.panel_type >= num_dtd) {
 		DRM_ERROR("Panel type %d not found in table of %d DTD's\n",
 			  dev_priv->vbt.panel_type, num_dtd);
 		return;