[U-Boot] v4 patch:SMDK6400: Fix some build bug

[seedshope]

Change from V1:
patch 1: 
patch 2: Delete some compile information from commit.
patch 3: Add LED modify information and Delete some compile information from commit.
patch 4: Add new patch for SDRAM init.

Change from v2:
patch2: Modify Makefile for arch/arm/cpu/arm1176/s3c64xx/cpu_init.s in build error.
It will generat redefine information for "mem_ctrl_asm_init" before the Modify.
patch4: Modify the Sergei Shtylyov comments and change the SDRAM size variable
for PHYS_SDRAM_SIZE_1.

Change from v3:
Add new patch 3: I discuss with Amicalement, I find the mutiple-link issue:
The first, the cpu_init.o have already been link for cmd_link_o_target
atfer compile. But, The link script re-link the point file. So the link
machine will generate multiple definition error information.
    
The second, Since the first 4kB of nand boot featue code move to nand_spl,
So It is not necessary to force the cpu_init.o in non-nand boot.

Delete the cpu_init.o from u-boot-nand.lds is safe.

patch 4: patch 4 and patch 5 is split from v2 patch4.
patch 6: Modify according Minkyu Kang comment