ata: simplify ata_scsiop_inq_89()

Initialize rbuf[] directly instead of using ata_tf_to_fis(). This
results in simpler and smaller code. It also allows separating
ata_tf_to_fis() into SATA specific libata part in the future.

Code size savings on m68k arch using (modified) atari_defconfig:

   text    data     bss     dec     hex filename
before:
  20824     105    4096   25025    61c1 drivers/ata/libata-scsi.o
after:
  20782     105    4096   24983    6197 drivers/ata/libata-scsi.o
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/ata/libata-scsi.c

@@ -2357,10 +2357,6 @@ static unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf)
  */
 static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf)
 {
-	struct ata_taskfile tf;
-
-	memset(&tf, 0, sizeof(tf));
-
 	rbuf[1] = 0x89;			/* our page code */
 	rbuf[2] = (0x238 >> 8);		/* page size fixed at 238h */
 	rbuf[3] = (0x238 & 0xff);
@@ -2369,14 +2365,14 @@ static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf)
 	memcpy(&rbuf[16], "libata          ", 16);
 	memcpy(&rbuf[32], DRV_VERSION, 4);
 
-	/* we don't store the ATA device signature, so we fake it */
-
-	tf.command = ATA_DRDY;		/* really, this is Status reg */
-	tf.lbal = 0x1;
-	tf.nsect = 0x1;
-
-	ata_tf_to_fis(&tf, 0, 1, &rbuf[36]);	/* TODO: PMP? */
 	rbuf[36] = 0x34;		/* force D2H Reg FIS (34h) */
+	rbuf[37] = (1 << 7);		/* bit 7 indicates Command FIS */
+					/* TODO: PMP? */
+
+	/* we don't store the ATA device signature, so we fake it */
+	rbuf[38] = ATA_DRDY;		/* really, this is Status reg */
+	rbuf[40] = 0x1;
+	rbuf[48] = 0x1;
 
 	rbuf[56] = ATA_CMD_ID_ATA;