Automatic merge from submit-queue (batch tested with PRs 47619, 47951, 46260, 48277)

iSCSi plugin: Remove redundant nil check

**What this PR does / why we need it**:

This patch is for cleanup of redundant nil check in iSCSI plugin.
This was mentioned at the code review on origin github thread.

https://github.com/openshift/origin/pull/14565

**Which issue this PR fixes** 

**Special notes for your reviewer**:

**Release note**:

```
NONE
```