Original code only support boot from LPC, now boot from SPI flash
is OK. Original code only support some spi command such as "spiid",
"spiprogram" and "spierase", now 4K-erase and othe sector size is
support. Original spi driver code can't save enviroment variable,
Now enviroment variable can be saved, and command such as "set" and
"unset" are both OK. By the way, now more SPI flash types are supported,
user just add flash type in "pmon/dev/flashdev.c".
Target:Bonito3c780e