ext4: ext4_put_super: Remove redundant checking for 'sbi->s_journal_bdev'

ext4: ext4_put_super: Remove redundant checking for 'sbi->s_journal_bdev'

As discussed in [1], 'sbi->s_journal_bdev != sb->s_bdev' will always
become true if sbi->s_journal_bdev exists. Filesystem block device and
journal block device are both opened with 'FMODE_EXCL' mode, so these
two devices can't be same one. Then we can remove the redundant checking
'sbi->s_journal_bdev != sb->s_bdev' if 'sbi->s_journal_bdev' exists.

[1] https://lore.kernel.org/lkml/f86584f6-3877-ff18-47a1-2efaa12d18b2@huawei.com/

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230315013128.3911115-3-chengzhihao1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>