blockdev: Don't use qerror_report_err() in drive_init()

blockdev: Don't use qerror_report_err() in drive_init()

qerror_report_err() is a transitional interface to help with
converting existing HMP commands to QMP.  It should not be used
elsewhere.

drive_init() is not meant to be used by QMP commands.  It uses both
qerror_report_err() and error_report().  Convert the former to the
latter.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>