ata: libata-acpi: Fix function name and provide description for 'prev_gtf'

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

 drivers/ata/libata-acpi.c:493: warning: expecting prototype for ata_acpi_gtm_xfermode(). Prototype was for ata_acpi_gtm_xfermask() instead
 drivers/ata/libata-acpi.c:648: warning: Function parameter or member 'prev_gtf' not described in 'ata_acpi_run_tf'

Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-ide@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210318085150.3131936-15-lee.jones@linaro.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/ata/libata-acpi.c

@@ -476,7 +476,7 @@ static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf)
 }
 
 /**
- * ata_acpi_gtm_xfermode - determine xfermode from GTM parameter
+ * ata_acpi_gtm_xfermask - determine xfermode from GTM parameter
  * @dev: target device
  * @gtm: GTM parameter to use
  *
@@ -624,6 +624,7 @@ static int ata_acpi_filter_tf(struct ata_device *dev,
  * ata_acpi_run_tf - send taskfile registers to host controller
  * @dev: target ATA device
  * @gtf: raw ATA taskfile register set (0x1f1 - 0x1f7)
+ * @prev_gtf: previous command
  *
  * Outputs ATA taskfile to standard ATA host controller.
  * Writes the control, feature, nsect, lbal, lbam, and lbah registers.