ata: let compiler optimize out ata_dev_config_ncq() on non-SATA hosts

Add !IS_ENABLED(CONFIG_SATA_HOST) to ata_dev_config_ncq() to allow
compiler to optimize out the function for non-SATA configs.

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

   text    data     bss     dec     hex filename
before:
  37582     572      40   38194    9532 drivers/ata/libata-core.o
after:
  36462     572      40   37074    90d2 drivers/ata/libata-core.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-core.c

@@ -2287,6 +2287,8 @@ static int ata_dev_config_ncq(struct ata_device *dev,
 		desc[0] = '\0';
 		return 0;
 	}
+	if (!IS_ENABLED(CONFIG_SATA_HOST))
+		return 0;
 	if (dev->horkage & ATA_HORKAGE_NONCQ) {
 		snprintf(desc, desc_sz, "NCQ (not used)");
 		return 0;