imagetool: replace image registration function by linker_lists feature

The registration was introduced in commit f86ed6a8d52c99bb2d17d3cac1647edca0c4399c

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>
diff --git a/tools/Makefile b/tools/Makefile
index e549f8e..cb44456 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -122,6 +122,8 @@
 HOSTLOADLIBES_fit_info := $(HOSTLOADLIBES_mkimage)
 HOSTLOADLIBES_fit_check_sign := $(HOSTLOADLIBES_mkimage)
 
+HOSTLDFLAGS += -T $(srctree)/tools/imagetool.lds
+
 hostprogs-$(CONFIG_EXYNOS5250) += mkexynosspl
 hostprogs-$(CONFIG_EXYNOS5420) += mkexynosspl
 HOSTCFLAGS_mkexynosspl.o := -pedantic