vmm: api: Make NetConfig defaults match between CLI and HTTP API

In order to let the CLI and the HTTP API behave the same regarding the
NetConfig structure, this patch defines some default values for tap, ip,
mask, mac and iommu.

tap is None, ip is 192.168.249.1, mask is 255.255.255.0, mac is a
randomly generated value, and iommu is false.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -279,18 +279,17 @@ components:
           default: false
 
     NetConfig:
-      required:
-      - ip
-      - mask
-      - mac
       type: object
       properties:
         tap:
           type: string
+          default: ""
         ip:
           type: string
+          default: "192.168.249.1"
         mask:
           type: string
+          default: "255.255.255.0"
         mac:
           type: string
         iommu: