build: disable initramfs build within image builder

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45673 3c298f89-4303-0410-b956-a3cf2f4a3e73

include/image.mk

@@ -362,6 +362,7 @@ define Device/Check
   _COMPILE_TARGET = $$(if $(CONFIG_IB)$$(filter $(PROFILE),$$(PROFILES)),compile,compile-disabled)
 endef
 
+ifndef IB
 define Device/Build/initramfs
   $$(_TARGET): $(BIN_DIR)/$$(KERNEL_INITRAMFS_IMAGE)
 
@@ -373,6 +374,7 @@ define Device/Build/initramfs
 	@rm -f $$@
 	$$(call concat_cmd,$$(KERNEL_INITRAMFS))
 endef
+endif
 
 define Device/Build/check_size
 	@[ $$(($(subst k,* 1024,$(subst m, * 1024k,$(1))))) -gt "$$(stat -c%s $@)" ] || { \