[libata] kill ATA_QCFLAG_POLL flag

The standard ATA bit nIEN in the Device Control register serves as
the indicator for whether we are polling or not.  As it mirrors
ATA_QCFLAG_POLL completely, eliminate that in favor of testing
ATA_NIEN bit.

drivers/scsi/libata-core.c

@@ -2733,7 +2733,7 @@ irqreturn_t ata_interrupt (int irq, void *dev_instance, struct pt_regs *regs)
 			struct ata_queued_cmd *qc;
 
 			qc = ata_qc_from_tag(ap, ap->active_tag);
-			if (qc && ((qc->flags & ATA_QCFLAG_POLL) == 0))
+			if (qc && (!(qc->tf.ctl & ATA_NIEN)))
 				handled += ata_host_intr(ap, qc);
 		}
 	}

drivers/scsi/sata_promise.c

@@ -421,7 +421,7 @@ static irqreturn_t pdc_interrupt (int irq, void *dev_instance, struct pt_regs *r
 			struct ata_queued_cmd *qc;
 
 			qc = ata_qc_from_tag(ap, ap->active_tag);
-			if (qc && ((qc->flags & ATA_QCFLAG_POLL) == 0))
+			if (qc && (!(qc->tf.ctl & ATA_NIEN)))
 				handled += pdc_host_intr(ap, qc);
 		}
 	}

drivers/scsi/sata_sx4.c

@@ -748,7 +748,7 @@ static irqreturn_t pdc20621_interrupt (int irq, void *dev_instance, struct pt_re
 			struct ata_queued_cmd *qc;
 
 			qc = ata_qc_from_tag(ap, ap->active_tag);
-			if (qc && ((qc->flags & ATA_QCFLAG_POLL) == 0))
+			if (qc && (!(qc->tf.ctl & ATA_NIEN)))
 				handled += pdc20621_host_intr(ap, qc, (i > 4),
 							      mmio_base);
 		}

drivers/scsi/sata_vsc.c

@@ -175,7 +175,7 @@ irqreturn_t vsc_sata_interrupt (int irq, void *dev_instance, struct pt_regs *reg
 				struct ata_queued_cmd *qc;
 
 				qc = ata_qc_from_tag(ap, ap->active_tag);
-				if (qc && ((qc->flags & ATA_QCFLAG_POLL) == 0))
+				if (qc && (!(qc->tf.ctl & ATA_NIEN)))
 					handled += ata_host_intr(ap, qc);
 			}
 		}

include/linux/libata.h

@@ -112,7 +112,6 @@ enum {
 	ATA_QCFLAG_DMA		= (1 << 2), /* data delivered via DMA */
 	ATA_QCFLAG_ATAPI	= (1 << 3), /* is ATAPI packet command? */
 	ATA_QCFLAG_SG		= (1 << 4), /* have s/g table? */
-	ATA_QCFLAG_POLL		= (1 << 5), /* polling, no interrupts */
 
 	/* various lengths of time */
 	ATA_TMOUT_EDD		= 5 * HZ,	/* hueristic */
@@ -483,7 +482,6 @@ static inline u8 ata_wait_idle(struct ata_port *ap)
 
 static inline void ata_qc_set_polling(struct ata_queued_cmd *qc)
 {
-	qc->flags |= ATA_QCFLAG_POLL;
 	qc->flags &= ~ATA_QCFLAG_DMA;
 	qc->tf.ctl |= ATA_NIEN;
 }