dm: switch to precise io accounting

hulk inclusion
category: bugfix
bugzilla: 188421, https://gitee.com/openeuler/kernel/issues/I7WMMI


CVE: NA

--------------------------------

'ios' and 'sectors' is counted in bio_start_io_acct() while io is
started insted of io is done. Hence switch to precise io accounting to
count them when io is done.

Signed-off-by: Li Nan <linan122@huawei.com>