Fix "--node-generic-resource" singular/plural

Daemon flags that can be specified multiple times use
singlar names for flags, but plural names for the configuration
file.

To make the daemon configuration know how to correlate
the flag with the corresponding configuration option,
`opt.NewNamedListOptsRef()` should be used instead of
`opt.NewListOptsRef()`.

Commit 6702ac590e6148cb3f606388dde93a011cb14931 attempted
to fix the daemon not corresponding the flag with the configuration
file option, but did so by changing the name of the flag
to plural.

This patch reverts that change, and uses `opt.NewNamedListOptsRef()`
instead.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 6e7715d65ba892a47d355e16bf9ad87fb537a2d0)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
diff --git a/cmd/dockerd/config.go b/cmd/dockerd/config.go
index c55332e..abdac9a 100644
--- a/cmd/dockerd/config.go
+++ b/cmd/dockerd/config.go
@@ -67,7 +67,7 @@
 
 	flags.StringVar(&conf.MetricsAddress, "metrics-addr", "", "Set default address and port to serve the metrics api on")
 
-	flags.Var(opts.NewListOptsRef(&conf.NodeGenericResources, opts.ValidateSingleGenericResource), "node-generic-resources", "Advertise user-defined resource")
+	flags.Var(opts.NewNamedListOptsRef("node-generic-resources", &conf.NodeGenericResources, opts.ValidateSingleGenericResource), "node-generic-resource", "Advertise user-defined resource")
 
 	flags.IntVar(&conf.NetworkControlPlaneMTU, "network-control-plane-mtu", config.DefaultNetworkMtu, "Network Control plane MTU")
 
diff --git a/cmd/dockerd/daemon_test.go b/cmd/dockerd/daemon_test.go
index e5e4aa3..b065831 100644
--- a/cmd/dockerd/daemon_test.go
+++ b/cmd/dockerd/daemon_test.go
@@ -61,6 +61,22 @@
 	testutil.ErrorContains(t, err, "as a flag and in the configuration file: labels")
 }
 
+func TestLoadDaemonCliWithConflictingNodeGenericResources(t *testing.T) {
+	tempFile := fs.NewFile(t, "config", fs.WithContent(`{"node-generic-resources": ["foo=bar", "bar=baz"]}`))
+	defer tempFile.Remove()
+	configFile := tempFile.Path()
+
+	opts := defaultOptions(configFile)
+	flags := opts.flags
+
+	assert.NoError(t, flags.Set("config-file", configFile))
+	assert.NoError(t, flags.Set("node-generic-resource", "r1=bar"))
+	assert.NoError(t, flags.Set("node-generic-resource", "r2=baz"))
+
+	_, err := loadDaemonCliConfig(opts)
+	testutil.ErrorContains(t, err, "as a flag and in the configuration file: node-generic-resources")
+}
+
 func TestLoadDaemonCliWithConflictingLabels(t *testing.T) {
 	opts := defaultOptions("")
 	flags := opts.flags