tg3: fix bug caused by uninitialized variable

The reported bug is caused by using mii_eee_cap1_mod_linkmode_t()
with an uninitialized bitmap. Fix this by zero-initializing the
struct containing the bitmap.

Fixes: 9bc79134 ("tg3: convert EEE handling to use linkmode bitmaps")
Reported-by: Srikanth Aithal <sraithal@amd.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -4616,7 +4616,7 @@ static int tg3_init_5401phy_dsp(struct tg3 *tp)
 
 static bool tg3_phy_eee_config_ok(struct tg3 *tp)
 {
-	struct ethtool_keee eee;
+	struct ethtool_keee eee = {};
 
 	if (!(tp->phy_flags & TG3_PHYFLG_EEE_CAP))
 		return true;