ext4: propagate errors from ext4_sb_bread() in ext4_xattr_block_cache_find()

In ext4_xattr_block_cache_find(), when ext4_sb_bread() returns an error,
we will either continue to find the next ea block or return NULL to try to
insert a new ea block. But whether ext4_sb_bread() returns -EIO or -ENOMEM,
the next operation is most likely to fail with the same error. So propagate
the error returned by ext4_sb_bread() to make ext4_xattr_block_set() fail
to reduce pointless operations.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240504075526.2254349-3-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>