erofs: don't warn MicroLZMA format anymore

The LZMA algorithm support has been landed for more than one year since
Linux 5.16.  Besides, the new XZ Utils 5.4 has been available in most
Linux distributions.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231021020137.1646959-1-hsiangkao@linux.alibaba.com