This reverts commit b201171f2b4d509f3ad510b214bee70ff902e3d6.
The commit caused problems for example when unpacking kernel images:
Uncompressing Kernel Image ... Error: inflate() returned -2
GUNZIP: uncompress, out-of-mem or overwrite error - must
RESET board to recover
Conflicts:
include/u-boot/zlib.h
lib_generic/zlib.c
Signed-off-by: Wolfgang Denk <wd@denx.de>