ata: dwc-ahci: change trace level for phy errors managed by uclass

As the error message is now displayed by generic phy functions,
the pr_err can be change to pr_debug.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/drivers/ata/dwc_ahci.c b/drivers/ata/dwc_ahci.c
index 825fe57..ed0527c 100644
--- a/drivers/ata/dwc_ahci.c
+++ b/drivers/ata/dwc_ahci.c
@@ -62,13 +62,13 @@
 
 	ret = generic_phy_init(&phy);
 	if (ret) {
-		pr_err("unable to initialize the sata phy\n");
+		pr_debug("unable to initialize the sata phy\n");
 		return ret;
 	}
 
 	ret = generic_phy_power_on(&phy);
 	if (ret) {
-		pr_err("unable to power on the sata phy\n");
+		pr_debug("unable to power on the sata phy\n");
 		return ret;
 	}