Add Flex-OneNAND booting support

Flex-OneNAND is a monolithic integrated circuit with a NAND Flash array
using a NOR Flash interface. This on-chip integration enables system designers
to reduce external system logic and use high-density NAND Flash
in applications that would otherwise have to use more NOR components.

Flex-OneNAND enables users to configure to partition it into SLC and MLC areas
in more flexible way. While MLC area of Flex-OneNAND can be used to store data
that require low reliability and high density, SLC area of Flex-OneNAND
to store data that need high reliability and high performance. Flex-OneNAND
can let users take advantage of storing these two different types of data
into one chip, which is making Flex-OneNAND more cost- and space-effective.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
diff --git a/Makefile b/Makefile
index 065ce90..4796f45 100644
--- a/Makefile
+++ b/Makefile
@@ -339,10 +339,12 @@
 		cat $(obj)nand_spl/u-boot-spl-16k.bin $(obj)u-boot.bin > $(obj)u-boot-nand.bin
 
 $(ONENAND_IPL):	$(VERSION_FILE)	$(obj)include/autoconf.mk
-		$(MAKE) -C onenand_ipl/board/$(BOARDDIR) all
+		$(MAKE) -C $(obj)onenand_ipl/board/$(BOARDDIR) all
 
 $(U_BOOT_ONENAND):	$(ONENAND_IPL) $(obj)u-boot.bin $(obj)include/autoconf.mk
+		$(MAKE) -C $(obj)onenand_ipl/board/$(BOARDDIR) all
 		cat $(obj)onenand_ipl/onenand-ipl-2k.bin $(obj)u-boot.bin > $(obj)u-boot-onenand.bin
+		cat $(obj)onenand_ipl/onenand-ipl-4k.bin $(obj)u-boot.bin > $(obj)u-boot-flexonenand.bin
 
 $(VERSION_FILE):
 		@( echo -n "#define U_BOOT_VERSION \"U-Boot " ; \
@@ -2873,7 +2875,7 @@
 	       $(obj)board/{integratorap,integratorcp}/u-boot.lds	  \
 	       $(obj)board/{bf533-ezkit,bf533-stamp,bf537-stamp,bf561-ezkit}/u-boot.lds
 	@rm -f $(obj)include/bmp_logo.h $(obj)nand_spl/{u-boot-spl,u-boot-spl.map}
-	@rm -f $(obj)onenand_ipl/onenand-{ipl,ipl.bin,ipl-2k.bin,ipl.map}
+	@rm -f $(obj)onenand_ipl/onenand-{ipl,ipl.bin,ipl-2k.bin,ipl-4k.bin,ipl.map}
 	@rm -f $(obj)api_examples/demo $(VERSION_FILE)
 	@find $(OBJTREE) -type f \
 		\( -name 'core' -o -name '*.bak' -o -name '*~' \