sfc: remove redundant variable old_vlan

Variable old_vlan is being assigned but is never used hence it is
and can be removed.

Cleans up clang warning:
warning: variable 'old_vlan' set but not used [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/sfc/ef10_sriov.c

···
 {
 	struct efx_ef10_nic_data *nic_data = efx->nic_data;
 	struct ef10_vf *vf;
-	u16 old_vlan, new_vlan;
+	u16 new_vlan;
 	int rc = 0, rc2 = 0;
 
 	if (vf_i >= efx->vf_count)
···
 	}
 
 	/* Do the actual vlan change */
-	old_vlan = vf->vlan;
 	vf->vlan = new_vlan;
 
 	/* Restore everything in reverse order */