ata/acard_ahci: remove unused variable n_elem

No one care the varible acard_ahci in func acard_ahci_qc_prep.
better to remove it.
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-ide@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/ata/acard-ahci.c

@@ -218,7 +218,6 @@ static enum ata_completion_errors acard_ahci_qc_prep(struct ata_queued_cmd *qc)
 	void *cmd_tbl;
 	u32 opts;
 	const u32 cmd_fis_len = 5; /* five dwords */
-	unsigned int n_elem;
 
 	/*
 	 * Fill in command table information.  First, the header,
@@ -232,9 +231,8 @@ static enum ata_completion_errors acard_ahci_qc_prep(struct ata_queued_cmd *qc)
 		memcpy(cmd_tbl + AHCI_CMD_TBL_CDB, qc->cdb, qc->dev->cdb_len);
 	}
 
-	n_elem = 0;
 	if (qc->flags & ATA_QCFLAG_DMAMAP)
-		n_elem = acard_ahci_fill_sg(qc, cmd_tbl);
+		acard_ahci_fill_sg(qc, cmd_tbl);
 
 	/*
 	 * Fill in command slot information.