The KERNEL_GZIP is used in most config and is the default, there is no
clear reason to diverge so let default be used.
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>