net: fsl_enetc: Introduce driver data

Introduce driver data for each PCI device. The driver data carry
offsets of registers which differ between different SoCs.

Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/drivers/net/fsl_enetc.h b/drivers/net/fsl_enetc.h
index 15408b6..b815474 100644
--- a/drivers/net/fsl_enetc.h
+++ b/drivers/net/fsl_enetc.h
@@ -168,6 +168,15 @@
 	struct phy_device *phy;
 };
 
+struct enetc_data {
+	/* Register layout offsets */
+	u16			reg_offset_pmr;
+	u16			reg_offset_psipmar;
+	u16			reg_offset_pcapr;
+	u16			reg_offset_psicfgr;
+	u16			reg_offset_mac;
+};
+
 /* PCS / internal SoC PHY ID, it defaults to 0 on all interfaces */
 #define ENETC_PCS_PHY_ADDR	0