net: NC-SI setup and handling

Add the handling of NC-SI ethernet frames, and add a check at the start
of net_loop() to configure NC-SI before starting other network commands.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/include/phy.h b/include/phy.h
index ad2096c..0737c4e 100644
--- a/include/phy.h
+++ b/include/phy.h
@@ -412,6 +412,8 @@
 		phydev->interface <= PHY_INTERFACE_MODE_QSGMII;
 }
 
+bool phy_interface_is_ncsi(void);
+
 /* PHY UIDs for various PHYs that are referenced in external code */
 #define PHY_UID_CS4340		0x13e51002
 #define PHY_UID_CS4223		0x03e57003