imagetool: replace image registration function by linker_lists feature

The registration was introduced in commit f86ed6a8d5

This commit also removes all registration functions, and the member "next"
from image_type_params struct

Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>

tools/imagetool.lds

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2011-2012 The Chromium OS Authors.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+SECTIONS
+{
+
+	. = ALIGN(4);
+	.u_boot_list : {
+		KEEP(*(SORT(.u_boot_list*)));
+	}
+
+	__u_boot_sandbox_option_start = .;
+	_u_boot_sandbox_getopt : { *(.u_boot_sandbox_getopt) }
+	__u_boot_sandbox_option_end = .;
+
+	__bss_start = .;
+}
+
+INSERT BEFORE .data;