[SCSI] qla2xxx: Double check for command completion if abort mailbox command fails.

Close a small window where we could falsely fail an abort request if the mailbox
command fails but the command was returned during interrupt context.

Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>