staging: erofs: support IO read error injection

Used to simulate disk IO read error for testing fatal
error tolerance.

Here are the details,
1) use bio->bi_private to indicate super_block
   for non-compressed bios since some (mainly meta)
   pages can be of the corresponding bdev inode;
2) get super_block dynamically for compressed bios,
   therefore it could not inject bios full of staging
   pages, yet it doesn't affect the normal usage.

Change-Id: I82830edeac0074abf83c3758e0b692b9bd1a96ae
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>