drm/panel: nt37801: Fix IS_ERR() vs NULL check in probe()

The devm_drm_panel_alloc() function returns error pointers, it doesn't
return NULL.  Update the check to match.

Fixes: 4fca684 ("drm/panel: Add Novatek NT37801 panel driver")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: Jessica Zhang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Dmitry Baryshkov <[email protected]>

Author: Dan Carpenter

drivers/gpu/drm/panel/panel-novatek-nt37801.c

@@ -257,8 +257,8 @@ static int novatek_nt37801_probe(struct mipi_dsi_device *dsi)
 	ctx = devm_drm_panel_alloc(dev, struct novatek_nt37801, panel,
 				   &novatek_nt37801_panel_funcs,
 				   DRM_MODE_CONNECTOR_DSI);
-	if (!ctx)
-		return -ENOMEM;
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
 
 	ret = devm_regulator_bulk_get_const(dev,
 					    ARRAY_SIZE(novatek_nt37801_supplies),