UPSTREAM: erofs: introduce on-disk lz4 fs configurations

Introduce z_erofs_lz4_cfgs to store all lz4 configurations.
Currently it's only max_distance, but will be used for new
features later.

Link: https://lore.kernel.org/r/20210329012308.28743-4-hsiangkao@aol.com


Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

Bug: 201372112
Change-Id: Ib9873b530bdc82f8cc5e79ac85ede737d883ff12
(cherry picked from commit 46249cde)
Signed-off-by: Huang Jianan <huangjianan@oppo.com>