ide: add ide_pad_transfer() helper

* Add ide_pad_transfer() helper (which uses ->{in,out}put_data methods
  internally so the transfer is also padded to drive+host requirements)
  and use it instead of ide_atapi_{write_zeros,discard_data}().

* Remove no longer needed ide_atapi_{write_zeros,discard_data}().

Cc: Borislav Petkov <petkovbb@gmail.com>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index 8d7c1a0..788783d 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -1642,3 +1642,18 @@
 }
 
 EXPORT_SYMBOL_GPL(ide_pktcmd_tf_load);
+
+void ide_pad_transfer(ide_drive_t *drive, int write, int len)
+{
+	ide_hwif_t *hwif = drive->hwif;
+	u8 buf[4] = { 0 };
+
+	while (len > 0) {
+		if (write)
+			hwif->output_data(drive, NULL, buf, min(4, len));
+		else
+			hwif->input_data(drive, NULL, buf, min(4, len));
+		len -= 4;
+	}
+}
+EXPORT_SYMBOL_GPL(ide_pad_transfer);