ide-tape: remove idetape_config_t typedef

Since this is used only in idetape_blkdev_ioctl(), remove the typedef and make
the struct function-local.

Bart:
- s/sizeof(struct idetape_config)/sizeof(config)/

Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>