toradex: Use checkboard() instead of show_board_info()

Boards can use a sysinfo driver if a particular model name is needed.
Update this board to use checkboard() directly, rather than having a
weak function laid on top of a weak function.

Make all the checkboard() functions call the new tdx_checkboard() so
that the same information is displayed.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/toradex/colibri-imx8x/colibri-imx8x.c b/board/toradex/colibri-imx8x/colibri-imx8x.c
index 6c0b097..d8cc72f 100644
--- a/board/toradex/colibri-imx8x/colibri-imx8x.c
+++ b/board/toradex/colibri-imx8x/colibri-imx8x.c
@@ -121,7 +121,7 @@
 	build_info();
 	print_bootinfo();
 
-	return 0;
+	return tdx_checkboard();
 }
 
 static void select_dt_from_module_version(void)