Linux 5.12 compat: replace bio_*_io_acct with disk_*_io_acct

The bio_*_acct functions became GPL exports, which causes the
kernel modules to refuse to compile. This replaces code with
alternate function calls to the disk_*_io_acct interfaces, which
are not GPL exports. This change was added in kernel commit
99dfc43ecbf67f12a06512918aaba61d55863efc.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #11639