imagebuilder: fix DEFAULT_PACKAGES handling

DEFAULT_PACKAGES handling was moved in commit 40be892a02
("imagebuilder: move handling of DEFAULT_PACKAGES into shareable place")
to `include/default-packages.mk`, but they weren't removed from
ImageBuilder's Makefile, so lets remove it now.

Once removed, I've noticed, that it stopped working as there is
target.mk included later in that file, overriding the DEFAULT_PACKAGES
again, so moved it after this target.mk include.

Fixes: 40be892a02 ("imagebuilder: move handling of DEFAULT_PACKAGES into shareable place")
Signed-off-by: Petr Štetiar <ynezz@true.cz>

target/imagebuilder/files/Makefile

@@ -26,7 +26,6 @@ include $(INCLUDE_DIR)/debug.mk
 include $(INCLUDE_DIR)/depends.mk
 include $(INCLUDE_DIR)/rootfs.mk
 
-include $(INCLUDE_DIR)/default-packages.mk
 include $(INCLUDE_DIR)/version.mk
 export REVISION
 export SOURCE_DATE_EPOCH
@@ -105,6 +104,7 @@ APK:=$(call apk,$(TARGET_DIR)) \
 
 
 include $(INCLUDE_DIR)/target.mk
+include $(INCLUDE_DIR)/default-packages.mk
 -include .profiles.mk
 
 USER_PROFILE ?= $(firstword $(PROFILE_NAMES))
@@ -139,11 +139,6 @@ _call_info: FORCE
 	echo 'Available Profiles:'
 	echo; $(PROFILE_LIST)
 
-ifneq ($(CONFIG_USE_APK),)
-  DEFAULT_PACKAGES += apk-mbedtls
-else
-  DEFAULT_PACKAGES += opkg
-endif
 BUILD_PACKAGES:=$(sort $(DEFAULT_PACKAGES) $($(USER_PROFILE)_PACKAGES) kernel)
 # "-pkgname" in the package list means remove "pkgname" from the package list
 BUILD_PACKAGES:=$(filter-out $(filter -%,$(BUILD_PACKAGES)) $(patsubst -%,%,$(filter -%,$(BUILD_PACKAGES))),$(BUILD_PACKAGES))