The LZO, LZ4, DEFLATE implementations in lib/ already check against
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS. Define this symbol defaulting to
0. This makes porting Kconfig symbols depending on it easier and in future,
we could select it from different arches.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>