ext4: extract ext4_has_journal_option() from __ext4_fill_super()

Extract the ext4_has_journal_option() helper function to reduce code
duplication. No functional changes.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250122110533.4116662-5-libaokun@huaweicloud.com


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