scsi-disk: qemu_vfree(NULL) is fine, simplify

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

hw/scsi-disk.c

@@ -85,9 +85,7 @@ static void scsi_free_request(SCSIRequest *req)
 {
     SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);
 
-    if (r->iov.iov_base) {
-        qemu_vfree(r->iov.iov_base);
-    }
+    qemu_vfree(r->iov.iov_base);
 }
 
 /* Helper function for command completion with sense.  */