net: phy: teranetics: Staticize PHY driver entries

These struct phy_driver ... instances are local to this source code
file, staticize them. No functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Acked-by: Michal Simek <michal.simek@amd.com>
Tested-by: Michal Simek <michal.simek@amd.com> #microblaze (MANUAL_RELOC)
diff --git a/drivers/net/phy/teranetics.c b/drivers/net/phy/teranetics.c
index 60049c2..c402bad 100644
--- a/drivers/net/phy/teranetics.c
+++ b/drivers/net/phy/teranetics.c
@@ -90,7 +90,7 @@
 	return 0;
 }
 
-struct phy_driver tn2020_driver = {
+static struct phy_driver tn2020_driver = {
 	.name = "Teranetics TN2020",
 	.uid = PHY_UID_TN2020,
 	.mask = 0xfffffff0,