LU-13814 lov: remove non-dio handling in lov_dio_submit

LU-13814 lov: remove non-dio handling in lov_dio_submit

lov_dio_submit is now specialized to dio.  Cleanup
accordingly.

Signed-off-by: Patrick Farrell <patrick.farrell@oracle.com>
Change-Id: I4e293011c77eb1b7b8f2c0ec78565458a6fe047c
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/52107
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Marc Vef <mvef@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Qian Yingjin <qian@ddn.com>