net: mventa: remove unused variable 'dummy' in mvneta_mib_counters_clear()

Fixes the following W=1 kernel build warning(s):

drivers/net/ethernet/marvell/mvneta.c:754:6: warning:
 variable 'dummy' set but not used [-Wunused-but-set-variable]
  754 |  u32 dummy;
      |      ^~~~~

This variable is not used in function mvneta_mib_counters_clear(), so
remove it to avoid build warning.
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvneta.c

@@ -751,13 +751,12 @@ static void mvneta_txq_inc_put(struct mvneta_tx_queue *txq)
 static void mvneta_mib_counters_clear(struct mvneta_port *pp)
 {
 	int i;
-	u32 dummy;
 
 	/* Perform dummy reads from MIB counters */
 	for (i = 0; i < MVNETA_MIB_LATE_COLLISION; i += 4)
-		dummy = mvreg_read(pp, (MVNETA_MIB_COUNTERS_BASE + i));
-	dummy = mvreg_read(pp, MVNETA_RX_DISCARD_FRAME_COUNT);
-	dummy = mvreg_read(pp, MVNETA_OVERRUN_FRAME_COUNT);
+		mvreg_read(pp, (MVNETA_MIB_COUNTERS_BASE + i));
+	mvreg_read(pp, MVNETA_RX_DISCARD_FRAME_COUNT);
+	mvreg_read(pp, MVNETA_OVERRUN_FRAME_COUNT);
 }
 
 /* Get System Network Statistics */