common.yaml: stop including ifcfg dracut module

It's included by default currently so we don't need this. A patch in FCOS
will actually make it so that we don't pull it in at all:
coreos/fedora-coreos-config#2642

Part of the move away `initramfs-args`, which is deprecated:
coreos/rpm-ostree#3834

common.yaml

@@ -40,8 +40,6 @@ initramfs-args:
   - "iscsi"
   - "ignition"
   - "--add"
-  - "ifcfg"
-  - "--add"
   - "fips"
 
 postprocess: