tg3: prevent use of uninitialized remote_adv and local_adv variables

Some execution paths that jump to the fiber_setup_done label
could leave the remote_adv and local_adv variables uninitialized
and then use it.

Initialize this variables at the point of definition to avoid this.

Fixes: 85730a6 ("tg3: Add SGMII phy support for 5719/5718 serdes")
Co-developed-by: Alexandr Sapozhnikov <alsp705@gmail.com>
Signed-off-by: Alexandr Sapozhnikov <alsp705@gmail.com>
Signed-off-by: Alexey Simakov <bigalex934@gmail.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://patch.msgid.link/20251014164736.5890-1-bigalex934@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: jtstrs

drivers/net/ethernet/broadcom/tg3.c

@@ -5803,7 +5803,7 @@ static int tg3_setup_fiber_mii_phy(struct tg3 *tp, bool force_reset)
 	u32 current_speed = SPEED_UNKNOWN;
 	u8 current_duplex = DUPLEX_UNKNOWN;
 	bool current_link_up = false;
-	u32 local_adv, remote_adv, sgsr;
+	u32 local_adv = 0, remote_adv = 0, sgsr;
 
 	if ((tg3_asic_rev(tp) == ASIC_REV_5719 ||
 	     tg3_asic_rev(tp) == ASIC_REV_5720) &&
@@ -5944,9 +5944,6 @@ static int tg3_setup_fiber_mii_phy(struct tg3 *tp, bool force_reset)
 		else
 			current_duplex = DUPLEX_HALF;
 
-		local_adv = 0;
-		remote_adv = 0;
-
 		if (bmcr & BMCR_ANENABLE) {
 			u32 common;