turris: 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.

Signed-off-by: Simon Glass <sjg@chromium.org>

board/CZ.NIC/turris_mox/turris_mox.c

@@ -562,7 +562,7 @@ static void handle_reset_button(void)
 	}
 }
 
-int show_board_info(void)
+int checkboard(void)
 {
 	int i, ret, board_version, ram_size, is_sd;
 	const char *pub_key, *model;

board/CZ.NIC/turris_omnia/turris_omnia.c

@@ -962,7 +962,7 @@ int board_late_init(void)
 	return 0;
 }
 
-int show_board_info(void)
+int checkboard(void)
 {
 	char serial[17];
 	int err;