kbuild: fix for updated LZ4 tool with the new streaming format

LZ4 has been updated with LZ4 Streaming Format specification(v1.3).
lz4demo is replaced by lz4c. lz4c supports both the new streaming and legacy format with -l
option. This patch makes use of lz4c to support
legacy format which is used for LZ4 De/compression in the linux kernel.
arm:add support for lz4 compressed kernel