ext4: factor out ext4_hash_info_init()

ext4: factor out ext4_hash_info_init()

commit db9345d9e6f075e1ec26afadf744078ead935fec upstream.

Factor out ext4_hash_info_init() to simplify __ext4_fill_super(). No
functional change.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-2-yanaijie@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Stable-dep-of: a2187431c395 ("ext4: fix error message when rejecting the default hash")
[cascardo: conflicts due to other parts of ext4_fill_super having been factored out]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>