drivers: net: ldpaa: export driver name and API to get DPMAC id

Export the ldpaa_eth_get_dpmac_id() function so that it can be used from
other drivers, especially by fsl-mc which will need it the next patch.
Also, create a macro for the Ethernet ldpaa driver name and export it as
well.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>

include/net/ldpaa_eth.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2023 NXP
+ */
+
+#define LDPAA_ETH_DRIVER_NAME	"ldpaa_eth"
+
+/**
+ * ldpaa_eth_get_dpmac_id() - Get the dpmac_id of a DPAA2 ethernet device
+ *
+ * @dev:	DPAA2 ethernet udevice pointer
+ * Return: requested dpmac_id
+ */
+
+uint32_t ldpaa_eth_get_dpmac_id(struct udevice *dev);