[U-Boot] [RFC 0/5] powerpc: Add support 2 stage boot loader for corenet platform

[Prabhakar Kushwaha]

Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
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Add support of 2 stage NAND boot loader in cornet platforms using SPL framework.
This will be helpful for those SoC which has less internal SRAM(128K).

here, PBL initialise the internal SRAM and copy SPL(96K) in SRAM. 
SPL further initialise DDR using SPD and environment variables and copy
u-boot(512 KB) from NAND flash to DDR.
Finally SPL transer control to u-boot for futher booting. 

SPL has following features:
 - Executes within 128K
 - SPL size 96K
 - No relocation required 

 Run time view of SPL framework
 ==============================
 -----------------------------------------------
 Area        | Address                         |
 -----------------------------------------------
 GD, BD      | 0xFFFE0000 (1K)                 |    
 -----------------------------------------------
 HEAP        | 0xFFFE0400 (26K) grow downwards |
 -----------------------------------------------
 STACK       | 0xFFFE8000 (5K)  grow upwards   |
 -----------------------------------------------
 U-boot SPL  | 0xfffe8000 – 0xfffffffc (96K)   |
 -----------------------------------------------

96K + 5K + 26K + 1K = 128K
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 This patch set contains:-

 [RFC 1/5] powerpc:Add support of SPL non-relocation

 [RFC 2/5] powerpc/SPL:Allow Parsing of LAW table in both SPL & non SPL
 
 [RFC 3/5] common/env: Point default envirenoment for GD
 
 [RFC 4/5] SPL:Defines function required to env read for IFC & env_nand
 
 [RFC 5/5] B4860QDS: Add support of 2 stage NAND boot loader
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1.7.9.5