enetc: remove variable 'tc_max_sized_frame' set but not used

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/ethernet/freescale/enetc/enetc_qos.c: In function enetc_setup_tc_cbs:
drivers/net/ethernet/freescale/enetc/enetc_qos.c:195:6: warning: variable tc_max_sized_frame set but not used [-Wunused-but-set-variable]

Fixes: c431047 ("enetc: add support Credit Based Shaper(CBS) for hardware offload")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/enetc/enetc_qos.c

@@ -192,7 +192,6 @@ int enetc_setup_tc_cbs(struct net_device *ndev, void *type_data)
 	u32 hi_credit_bit, hi_credit_reg;
 	u32 max_interference_size;
 	u32 port_frame_max_size;
-	u32 tc_max_sized_frame;
 	u8 tc = cbs->queue;
 	u8 prio_top, prio_next;
 	int bw_sum = 0;
@@ -250,7 +249,7 @@ int enetc_setup_tc_cbs(struct net_device *ndev, void *type_data)
 		return -EINVAL;
 	}
 
-	tc_max_sized_frame = enetc_port_rd(&si->hw, ENETC_PTCMSDUR(tc));
+	enetc_port_rd(&si->hw, ENETC_PTCMSDUR(tc));
 
 	/* For top prio TC, the max_interfrence_size is maxSizedFrame.
 	 *