qcacld-3.0: Add NULL check for adapter->vdev in interop_ap

In the function __wlan_cfg80211_set_interop_issues_ap_config the
adapter->vdev pointer is being passed to fetch the psoc without any
prior NULL check. This can lead to NULL pointer dereference.

Add a NULL sanity check before performing action based on adapter->vdev

CRs-Fixed: 2681524
Change-Id: I0c58a3a263fe5166e0c13a5f866f4bccfa031086