scsi: qla4xxx: drop redundant init_completion

The redundant init_completion() here seems to be a cut&past error as
struct scsi_qla_host only has 4 completion elements to initialize, thus
the duplicate init_completion(disable_acb_comp) is simply removed.

Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>