cmd: Add unlz4 command

This command is a new command called "unlz4" that decompresses from memory
into memory.
Used with the CONFIG_CMD_UNLZ4 optionenabled.

Signed-off-by: Yusuke Ashiduka <ashiduka@fujitsu.com>
[trini: Use %zd / %zX not %ld / %lX in printf]
Signed-off-by: Tom Rini <trini@konsulko.com>
3 files changed