ext4: make ext4_zeroout_es() return void

After ext4_es_insert_extent() returns void, the return value in
ext4_zeroout_es() is also unnecessary, so make it return void too.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230424033846.4732-13-libaokun1@huawei.com


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