net: dwc_eth_qos: Make eqos_get_tick_clk_rate callback optional

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/dwc_eth_qos.c b/drivers/net/dwc_eth_qos.c
index afc47b5..753a912 100644
--- a/drivers/net/dwc_eth_qos.c
+++ b/drivers/net/dwc_eth_qos.c
@@ -774,10 +774,13 @@
 		pr_err("eqos_calibrate_pads() failed: %d", ret);
 		goto err_stop_resets;
 	}
-	rate = eqos->config->ops->eqos_get_tick_clk_rate(dev);
+
+	if (eqos->config->ops->eqos_get_tick_clk_rate) {
+		rate = eqos->config->ops->eqos_get_tick_clk_rate(dev);
 
-	val = (rate / 1000000) - 1;
-	writel(val, &eqos->mac_regs->us_tic_counter);
+		val = (rate / 1000000) - 1;
+		writel(val, &eqos->mac_regs->us_tic_counter);
+	}
 
 	/*
 	 * if PHY was already connected and configured,