jbd2: remove unneeded check of ret in jbd2_fc_get_buf

Simply return -EINVAL if j_fc_off is invalid to avoid repeated check of
ret.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20240801013815.2393869-9-shikemeng@huaweicloud.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>