lib/decompress_unlzo: use fill and full to read and write data ...

this will all to simplify the sync with the kernel and later easly add the
self decompression support to barebox

as example with a lzo compression will reduce barebox from 180224 to 99863
bytes so 55.41%
-rwxr-xr-x 1 root root  99863 Jan 28 02:17 build/versatilepb/barebox.bin.lzo

we also reduce the binary size by 224 bytes

Old version
# ls -al build/versatilepb/barebox.bin
-rwxr-xr-x 1 root root 180468 Jan 28 02:14 build/versatilepb/barebox.bin

New version
# ls -al build/versatilepb/barebox*
-rwxr-xr-x 1 root root 180244 Jan 28 02:13 build/versatilepb/barebox.bin

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

add unlzo support ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>