ide: remove ide_drive_t.usage

This field is no longer used by the core IDE code so fix ide-{disk,floppy}
drivers to keep openers count in the driver specific objects and remove
it from ide-{cd,scsi,tape} drivers (it was write-only).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index e6e350c..624d488 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -3353,21 +3353,16 @@
 {
 	struct gendisk *disk = inode->i_bdev->bd_disk;
 	struct cdrom_info *info;
-	ide_drive_t *drive;
 	int rc = -ENOMEM;
 
 	if (!(info = ide_cd_get(disk)))
 		return -ENXIO;
 
-	drive = info->drive;
-
-	drive->usage++;
-
 	if (!info->buffer)
-		info->buffer = kmalloc(SECTOR_BUFFER_SIZE,
-					GFP_KERNEL|__GFP_REPEAT);
-        if (!info->buffer || (rc = cdrom_open(&info->devinfo, inode, file)))
-		drive->usage--;
+		info->buffer = kmalloc(SECTOR_BUFFER_SIZE, GFP_KERNEL|__GFP_REPEAT);
+
+	if (info->buffer)
+		rc = cdrom_open(&info->devinfo, inode, file);
 
 	if (rc < 0)
 		ide_cd_put(info);
@@ -3379,10 +3374,8 @@
 {
 	struct gendisk *disk = inode->i_bdev->bd_disk;
 	struct cdrom_info *info = ide_cd_g(disk);
-	ide_drive_t *drive = info->drive;
 
 	cdrom_release (&info->devinfo, file);
-	drive->usage--;
 
 	ide_cd_put(info);