net: dwc_eth_qos: Adapt probe() for PCI devices

PCI devices do not necessarily use a device tree. In that case, the
driver currently fails to find eqos->config and eqos->regs.

This commit factors out the respective functionality. Device tree usage
remains default, but board specific implementations will be possible as
well.

Signed-off-by: Philip Oberfichtner <pro@denx.de>
diff --git a/drivers/net/dwc_eth_qos_starfive.c b/drivers/net/dwc_eth_qos_starfive.c
index 09e714c..d9ace43 100644
--- a/drivers/net/dwc_eth_qos_starfive.c
+++ b/drivers/net/dwc_eth_qos_starfive.c
@@ -183,6 +183,12 @@
 	struct starfive_platform_data *data;
 	int ret;
 
+	ret = eqos_get_base_addr_dt(dev);
+	if (ret) {
+		pr_err("eqos_get_base_addr_dt failed: %d\n", ret);
+		return ret;
+	}
+
 	data = calloc(1, sizeof(struct starfive_platform_data));
 	if (!data)
 		return -ENOMEM;