All erase commands are done for SPI flash
copy command (cp) working, u-boot can load a firmware via tftp, erase a region of SPI flash, copy the firmware (previously load via tftp in SDRAM) in SPI flash and run it !
Still some work to do :
erase function : condition (if already = 0xFFFFFFFF, do nothing)
detect spi flash sectors size automatically
use flash_info_t structure (not really necessary but can make some things run better)
BUG : > erase 14000000 +1