Add Nand Flash support for MINI2440, It can boot both from Nor Flash and Nand Flash.
After boot from Nor Flash, use u-boot command "nand write 0 0 60000" to write u-boot binary from SDRAM to Nand Flash, then it can be booted from Nand Flash.
[u-boot@MINI2440] # nand write 0 0 60000

NAND write: device 0 offset 0x0, size 0x60000
NAND write to offset 0 failed -5
 262144 bytes written: ERROR
 [u-boot@MINI2440] # ~

 U-Boot 2010.06-dirty (Aug 10 2014 - 11:22:37)

 DRAM:  64 MiB
 Flash: 2 MiB
 NAND:  256 MiB
 *** Warning - bad CRC or NAND, using default environment

 In:    serial
 Out:   serial
 Err:   serial
 Net:   CS8900-0
 [u-boot@MINI2440] # saveenv
 Saving Environment to NAND...
 Erasing Nand...
 Erasing at 0x60000 -- 100% complete.
 Writing to Nand... done
 [u-boot@MINI2440] # reset
 resetting ...

 U-Boot 2010.06-dirty (Aug 10 2014 - 11:22:37)

 DRAM:  64 MiB
 Flash: 2 MiB
 NAND:  256 MiB
 In:    serial
 Out:   serial
 Err:   serial
 Net:   CS8900-0
 [u-boot@MINI2440] #