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/atmelimage.c

@@ -324,19 +324,17 @@ static int atmel_vrec_header(struct image_tool_params *params,
 	return EXIT_SUCCESS;
 }
 
-static struct image_type_params atmelimage_params = {
-	.name		= "ATMEL ROM-Boot Image support",
-	.header_size	= 0,
-	.hdr		= NULL,
-	.check_image_type = atmel_check_image_type,
-	.verify_header	= atmel_verify_header,
-	.print_header	= atmel_print_header,
-	.set_header	= atmel_set_header,
-	.check_params	= atmel_check_params,
-	.vrec_header	= atmel_vrec_header,
-};
-
-void init_atmel_image_type(void)
-{
-	register_image_type(&atmelimage_params);
-}
+U_BOOT_IMAGE_TYPE(
+	atmelimage,
+	"ATMEL ROM-Boot Image support",
+	0,
+	NULL,
+	atmel_check_params,
+	atmel_verify_header,
+	atmel_print_header,
+	atmel_set_header,
+	NULL,
+	atmel_check_image_type,
+	NULL,
+	atmel_vrec_header
+);