neutron-legacy: Consistently use `--config-file foo`

This change adjusts a few instances of `--config-file=foo` to
`--config-file foo` (no `=`) in order to make neutron command
lines more consistent and easier to match in sudoers/rootwrap
filters.

This is particularly useful for oslo.privsep, which needs to start a
helper command with the same `--config-file` arguments (see
Ia9675dff9232e0e987a836ecaf9e842eb5c3cb18).

Change-Id: I91fe18f66f3c3bc2ccd1ca8be91be2915ed3e3ec
diff --git a/lib/neutron_plugins/services/l3 b/lib/neutron_plugins/services/l3
index a5a6c81..3a6f6eb 100644
--- a/lib/neutron_plugins/services/l3
+++ b/lib/neutron_plugins/services/l3
@@ -83,7 +83,7 @@
 SUBNETPOOL_SIZE_V6=${SUBNETPOOL_SIZE_V6:-64}
 
 function _determine_config_l3 {
-    local opts="--config-file $NEUTRON_CONF --config-file=$Q_L3_CONF_FILE"
+    local opts="--config-file $NEUTRON_CONF --config-file $Q_L3_CONF_FILE"
     echo "$opts"
 }