[U-Boot] S3c64xx: Switch all I/O to use readl/writel function

[Zhong Hongbo]

This serial patch intent to:
1. Switch all I/O to use readl/writel function
2. Change nand_spl to use SPL framework
3. S3C64XX serial includes s3c6400 and s3c6410,
Here seprate cpu and board file to support to board's of s3c6410.


I test this patch on my s3c6410 development board. the log as following:

U-Boot 2012.04.01-10905-g9fa0c77 (Jul 07 2012 - 15:50:57) for SMDK6400


CPU:     S3C64XX at 532MHz
         Fclk = 532MHz, Hclk = 133MHz, Pclk = 66MHz (ASYNC Mode) 
Board:   DMATEK6410
DRAM:  128 MiB
WARNING: Caches not enabled
NAND:  128 MiB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   dm9000
Hit any key to stop autoboot:  0 
DMATEK6410 #