board/b4qds:Add support of 2 stage NAND boot-loader

Add support of 2 stage NAND boot loader using SPL framework.
here, PBL initialise the internal SRAM and copy SPL(160KB). This further
initialise DDR using SPD and environment and copy u-boot(768 KB) from NAND to DDR.
Finally SPL transer control to u-boot.

Initialise/create followings required for SPL framework
  - Add spl.c which defines board_init_f, board_init_r
  - update tlb and ddr accordingly

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/board/freescale/b4860qds/Makefile b/board/freescale/b4860qds/Makefile
index e5cc054..0acd2a9 100644
--- a/board/freescale/b4860qds/Makefile
+++ b/board/freescale/b4860qds/Makefile
@@ -4,9 +4,14 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+ifdef CONFIG_SPL_BUILD
+obj-y += spl.o
+else
 obj-y	+= b4860qds.o
-obj-y	+= ddr.o
 obj-$(CONFIG_B4860QDS)+= eth_b4860qds.o
-obj-$(CONFIG_PCI)	+= pci.o
+obj-$(CONFIG_PCI)      += pci.o
+endif
+
+obj-y	+= ddr.o
 obj-y	+= law.o
 obj-y	+= tlb.o